Installing MoBo

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

<fder.nospam@home.nl> wrote:

>I'm trying to build my first home-build computer.(Asus A7N8X-E)
>And now I have a question about how I do installing my MoBo in the
>case.I have fit those copper things to keep the distants between
>the case and the MoBo.

The distance is so that the underside of the mainboard does not
contact the metal case.

>On the MoBo side I have to fit these little ring for the electrical
>insulation (or is this isolation!!!)
>Whatever, my question is:o I fit those rings on both sides, or
>just on the top side of the MoBo.

Maybe neither. Did you get those rings from some shop?

Modern mainboard's are designed to be grounded at those points (I'm
not saying it's absolutely necessary).

http://usa.asus.com/products/mb/so [...] -e-d_l.jpg

In the picture, you can see silver colored electrically conductive
circles around the mainboard mounting holes. Those are ground
points, they are connected directly to device ground pins on the
mainboard. Power supply and mainboard ground are connected to the
case. There's no reason to insulate those points. Of course you
might want to avoid overtightening the screws or using screws which
have very big heads.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

<fder.nospam@home.nl> wrote in news:cnvj3f$d0r$1@news1.zwoll1.ov.home.nl:

> Hi All
>
> I'm trying to build my first home-build computer.(Asus A7N8X-E)
> And now I have a question about how I do installing my MoBo in the
> case.I have fit those copper things to keep the distants between the
> case and the MoBo.On the MoBo side I have to fit these little ring for
> the electrical insulation (or is this isolation!!!)
> Whatever, my question is:o I fit those rings on both sides, or just on
> the top side of the MoBo.
>
> Thx in advance
> françois
>
>
>

I agree with the other advice. Also read the manual for the ASUS
motherboard. There are several jumpers that must be set correctly if you
want the system to work.

http://www.buildyourown.org.uk/
http://www.pcmech.com/byopc/index.htm
http://www.quepublishing.com/promotion/1626
http://www.asus.com.tw/support/dow [...] 2_id=10&l3
_id=23&m_id=2&f_name=e1293_a7n8x.zip~zaqwedc
or for the linewrap retarded: http://tinyurl.com/5e6l8


Mike


--
"All my friends can't be wrong!"
Remember, stupidity runs in herds.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Washers: Generally made of plastic or paper, these go under the screws
to keep the screw head away from the circuitry on the top surface of
the motherboard. These are now sometimes being omitted in new system
cases because they are less necessary now than they once were (since
motherboards today now tend to keep the circuitry farther away from
the screwholes than they once did).

http://www.pcguide.com/ref/case/partsHardware-c.html




<fder.nospam@home.nl> wrote in message
news:cnvj3f$d0r$1@news1.zwoll1.ov.home.nl...
> Hi All
>
> I'm trying to build my first home-build computer.(Asus A7N8X-E)
> And now I have a question about how I do installing my MoBo in the
case.I
> have fit those copper things to keep the distants between the case
and the
> MoBo.On the MoBo side I have to fit these little ring for the
electrical
> insulation (or is this isolation!!!)
> Whatever, my question is:o I fit those rings on both sides, or
just on the
> top side of the MoBo.
>
> Thx in advance
> françois
>
>

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

For every mb that I've built in the last 4 years I have not used any fiber
or copper washers top or bottom. I would suggest you ignore them completely
in your build. Simply take care to tighten but not overdo it. If you come
across a spot on the mounting plate of the case that there is no dimple or
needs a screw in or squeeze on spacer to mount your mb then use what came
with the case. That should be all that's necessary.

--
Jan Alter
bearpuf@verizon.net
or
jalter@phila.k12.pa.us
"Al Smith" <invalid@address.com> wrote in message
news:AqLod.184108$Np3.7450790@ursa-nb00s0.nbnet.nb.ca...
>> I'm trying to build my first home-build computer.(Asus A7N8X-E)
>
> Good choice.
>
>> And now I have a question about how I do installing my MoBo in the case.I
>> have fit those copper things to keep the distants between the case and
>> the
>> MoBo.
>
> Be very careful that you don't put a brass spacer somewhere behind the
> board, then forget it's there when you fit the motherboard into the case.
> It could short out the board if it makes contact with the circuits on the
> back. Just keep track of them and make sure you have a screw hole on the
> motherboard for each spacer you put onto the case.
>
> On the MoBo side I have to fit these little ring for the electrical
>> insulation (or is this isolation!!!)
>> Whatever, my question is:o I fit those rings on both sides, or just on
>> the
>> top side of the MoBo.
>
> Those little paper rings are just extras. You don't need them. The board
> is designed to be insulated from the brass spacers at the screw holes.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

<fder.nospam@home.nl> wrote in message news:<cnvj3f$d0r$1@news1.zwoll1.ov.home.nl>...

> I'm trying to build my first home-build computer.
> (Asus A7N8X-E) And now I have a question about how
> I do installing my MoBo in the case. I have fit
> those copper things to keep the distants between the
> case and the MoBo. On the MoBo side I have to fit
> these little ring for the electrical insulation (or
> is this isolation!!!)
> do I fit those rings on both sides, or just on the
> top side of the MoBo.

The copper things are actually brass and called "standoffs."

When in doubt, install those rings (fiber washers) on both sides of
each hole because if you leave out a needed washer, the motherboard
will short to ground and possibly be damaged. On the other hand if
you install unneeded washers you'll simply waste some time and washers
and have marginally worse immunity to electrical noise.

Nobody should make a blanket recommendation about insulator washers
and all motherboards, and each board must be inspected individually.
If a side of a mounting hole is surrounded by a copper donut (usually
has 6 tiny holes around it, may be coated with solder) or is
completely clear of any copper (neither standoff nor screw can
possibly touch copper traces), then it doesn't need an insulator
washer. Motherboards made in the past 5 years rarely need insulators
but I've seen exceptions as new as 12 months old.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Motherboard and chassis grounds should not be electrically
connected at multiple points. Concept is called single point
grounding - also used to make A/D converters work reliable and
to eliminate hum among stereo components. An experiment
easily demonstrates the problem if you can make 'painful'
static electricity.

Put the computer on a glass table top (because even wood is
an electrical conductor). While computer is running, static
discharge your body to various corners of a computer chassis.
Computer should work just fine and uninterrupted. However, if
the motherboard ground has too many electrical connections to
chassis, then computer will crash.

The one electrically conductive standoff 'motherboard to
chassis' should be in same area as power connector and IO
boards. When normal static electric discharges occur, then
two electrically conductive paths from chassis to motherboard
ground do not conduct that static discharge via motherboard
ground plane.

Nylon standoffs are the simple solution. Motherboard's
green solder mask is not intended to be an electrical
insulator (even though some assume so). Nylon shoulder
washers keep metallic standoffs from penetrating the solder
mask; from making motherboard ground contact. But simpler is
to obtain 'snap in' nylon standoffs to eliminate accidental
shorts to motherboard AND to make computer resistant to static
electric induced crashes.

fder.nospam@home.nl wrote:
> Thank you guys.
> you were a big help.
> <fder.nospam@home.nl> schreef in bericht
> news:cnvj3f$d0r$1@news1.zwoll1.ov.home.nl...

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

In the junior high school lunch room, where basic knowledge
is minimal, the child learns how insults can replace fact.
However adults learn facts before posting. If John Doe had
basic electrical knowledge, then he would have discovered
numerous references to single point grounding. Instead, John
Doe searched newsgroups (not the web) for electrical
principals he never bothered to learn.

A John Doe educated in simple electrical concepts would have
found numerous engineering discussions about single point
ground. One from Microchip - a microprocessor manufacturer:
http://www.microchipc.com/PIC_tips_3.asp
> The best way to handle the ground problem is to have different
> ground systems that connect at only one point. The precision
> analog REFERENCE ground should always be designed so that an
> absolute minimum of current actually flows through it. In
> practice this is accomplished by having all reference ground
> connections terminating at a SINGLE POINT.

This is but one example. Literally every electronic part
manufacturer provides application notes that teach variations
of the single point grounding. Again, in stereo and PA
systems, the same concept eliminates something called ground
loops.

I don't know who John Doe is. But quickly he does what kids
in a lunch room do. Kids don't know facts, so instead, they
attack the messenger. John Doe obviously does not possess
basic electrical knowledge. He demonstrates why so many
computer assemblers are 'experts' - needs no freaking
education.

Don't be mislead by the naive. Make a computer systems more
reliable. A connection between motherboard logic ground and
chassis ground should be single point. With dry weather
approaching, the previously posted static electricity
experiment can demonstrate the principles. Notice the
difference between this poster and John Doe. This poster
cites professional sources AND provides experiments (static
shock a computer, or stereo system ground loops) to
demonstrate the electrical concept.

That keyboard beneath your fingers uses same single point
ground concepts. Pin 3 or pin 4 is the DC ground. Connector
shell and shield inside wire connects to DC ground at a single
point. Why? Some keyboards go even farther to keep shield
ground separate from DC ground until both meet, instead, at
motherboard. Just another example of single point grounds to
avoid failures from static electricity and noise. Two
separate grounds that meet at a common point.

Single point ground justified by electrical reasons - when
one first learns these basic electrical principles. This post
includes design examples AND the principles behind that
design. Principles that apparently so confused John Doe that
he searches newsgroups for a technical explanation rather than
consult engineering books or engineering application notes.

Best to mount a motherboard to chassis with only one
connection between the two grounds. Eliminate noise between
ground pins of computer's Integrated Circuits to make computer
more reliable. No ground transients through motherboard logic
ground means a stable computer system. Motherboard logic
ground best joins chassis ground at a single point using a
single conductive standoff.

John Doe wrote:
> The term "single point grounding" is buzzword nonsense in this
> context. The reader can do a Usenet archive search for "single point
> grounding" and then scroll down the page, noticing most of the posts
> were made by "w_tom".
>
> Antec cases come with no washers, but they come with electrically
> conducting brass mainboards standoffs. Microstar International and
> Asus mainboards have electricity conductive solder coated rings
> around their mounting holes which are directly connected to device
> ground pins, and they do not come with washers either.
>
> You don't have to be a rocket scientist to figure out what that
> means.
>
> If what you are saying were true, which it isn't, given the contrary
> circumstances, motherboard/mainboard makers would advise us to use
> insulation. Clearly, we are expected to ground the mainboard at
> those points. (I am speaking about mainboards which have electricity
> conductive rings around their mounting holes.)
>
> > Nylon standoffs are the simple solution.
>
> They would be, if what you're saying were true. Nylon standoffs
> would be cheaper than electricity conducting brass standoffs also.
>
> > Motherboard's green solder mask is not intended to be an
> > electrical insulator (even though some assume so).
>
> Electricity conductive mounting hole rings are not intended to be
> electrical insulators either. The idea that any manufacturer would
> use electricity conductive material for an insulator is bizarre in
> my opinion.
>
> >Path: newssvr30.news.prodigy.com!newsdbm03.news.prodigy.com!newsdst02.news.prodigy.com!newsmst01a.news.prodigy.com!prodigy.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local1.nntp.dca.giganews.com!nntp.nni.com!news.nni.com.POSTED!not-for-mail
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> >Date: Wed, 24 Nov 2004 11:33:49 -0500
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> >Subject: Re: Installing MoBo
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Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

w_tom wrote:

> In the junior high school lunch room, where basic knowledge
> is minimal, the child learns how insults can replace fact.
> However adults learn facts before posting. If John Doe had
> basic electrical knowledge, then he would have discovered
> numerous references to single point grounding. Instead, John
> Doe searched newsgroups (not the web) for electrical
> principals he never bothered to learn.
>
> A John Doe educated in simple electrical concepts would have
> found numerous engineering discussions about single point
> ground. One from Microchip - a microprocessor manufacturer:
> http://www.microchipc.com/PIC_tips_3.asp

That's a typical analog single point circuit ground, the primary purpose
being to isolate the analog section from the digital section's switching
induced ground noise; which has nothing to do with chassis/motherboard
shield grounding.

It is intuitively obvious to even the most casual observer, however, that a
9.6 inch by 9.6 inch ground planed mATX motherboard does not present a
'single point ground' to it's components. The point being, while a 'single
point ground' has specific uses, to then go dancing around claiming it's
'the solution' to everything under the sun is to not understand it.


>>The best way to handle the ground problem is to have different
>>ground systems that connect at only one point. The precision
>>analog REFERENCE ground should always be designed so that an
>>absolute minimum of current actually flows through it. In
>>practice this is accomplished by having all reference ground
>>connections terminating at a SINGLE POINT.
>
>
> This is but one example. Literally every electronic part
> manufacturer provides application notes that teach variations
> of the single point grounding. Again, in stereo and PA
> systems, the same concept eliminates something called ground
> loops.

Yes, single point ground techniques are well known. It is also well known
that single point grounding is only effective with < 1 Mhz signals (in
general) and, in case anyone failed to notice, PC's passed that mark with
the very first one (not to mention that switching transients generate much
higher frequencies than the 'clock' rates).

'Single point ground' becomes useless at high frequencies because, while
the potential is '0' at the 'single point ground', the induced field is a
maximum 1/4 (and every odd quarter) wavelength from the 'single point
ground'; not that it need be 'maximum' to be a problem. If you can't get it
done in well under 1/20 wavelength then you need another solution.


> I don't know who John Doe is. But quickly he does what kids
> in a lunch room do. Kids don't know facts, so instead, they
> attack the messenger.

You certainly out did him on that score.

> John Doe obviously does not possess
> basic electrical knowledge. He demonstrates why so many
> computer assemblers are 'experts' - needs no freaking
> education.
>
> Don't be mislead by the naive. Make a computer systems more
> reliable. A connection between motherboard logic ground and
> chassis ground should be single point. With dry weather
> approaching, the previously posted static electricity
> experiment can demonstrate the principles. Notice the
> difference between this poster and John Doe. This poster
> cites professional sources AND provides experiments (static
> shock a computer, or stereo system ground loops) to
> demonstrate the electrical concept.
>
> That keyboard beneath your fingers uses same single point
> ground concepts. Pin 3 or pin 4 is the DC ground. Connector
> shell and shield inside wire connects to DC ground at a single
> point. Why? Some keyboards go even farther to keep shield
> ground separate from DC ground until both meet, instead, at
> motherboard. Just another example of single point grounds to
> avoid failures from static electricity and noise. Two
> separate grounds that meet at a common point.
>
> Single point ground justified by electrical reasons - when
> one first learns these basic electrical principles. This post
> includes design examples AND the principles behind that
> design. Principles that apparently so confused John Doe that
> he searches newsgroups for a technical explanation rather than
> consult engineering books or engineering application notes.

For someone who pontificates so much about learning electrical principles
you sure jumble them up all over the place, scrambling analog, digital, low
frequency, high frequency, power, cable interconnect, circuit ground,
chassis ground, protective ground, and EMI shielding into a hodge podge of
misapplication.


> Best to mount a motherboard to chassis with only one
> connection between the two grounds. Eliminate noise between
> ground pins of computer's Integrated Circuits to make computer
> more reliable. No ground transients through motherboard logic
> ground means a stable computer system. Motherboard logic
> ground best joins chassis ground at a single point using a
> single conductive standoff.

John Doe's observation of metal standoffs and a motherboard manufacturer
controlling whether or not their mounting holes are intentionally connected
to the board's ground plane, or not, is spot on and makes the point moot.

If a 'single point ground' is desirable then the manufacturer will make a
'single point' the ground connection, or provide installation instructions
on what the assembler should do to ensure it.

>
> John Doe wrote:
>
>>The term "single point grounding" is buzzword nonsense in this
>>context. The reader can do a Usenet archive search for "single point
>>grounding" and then scroll down the page, noticing most of the posts
>>were made by "w_tom".
>>
>>Antec cases come with no washers, but they come with electrically
>>conducting brass mainboards standoffs. Microstar International and
>>Asus mainboards have electricity conductive solder coated rings
>>around their mounting holes which are directly connected to device
>>ground pins, and they do not come with washers either.
>>
>>You don't have to be a rocket scientist to figure out what that
>>means.
>>
>>If what you are saying were true, which it isn't, given the contrary
>>circumstances, motherboard/mainboard makers would advise us to use
>>insulation. Clearly, we are expected to ground the mainboard at
>>those points. (I am speaking about mainboards which have electricity
>>conductive rings around their mounting holes.)
>>
>>
>>> Nylon standoffs are the simple solution.
>>
>>They would be, if what you're saying were true. Nylon standoffs
>>would be cheaper than electricity conducting brass standoffs also.
>>
>>
>>>Motherboard's green solder mask is not intended to be an
>>>electrical insulator (even though some assume so).
>>
>>Electricity conductive mounting hole rings are not intended to be
>>electrical insulators either. The idea that any manufacturer would
>>use electricity conductive material for an insulator is bizarre in
>>my opinion.
>>

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Grounding concepts in that cited microchip discussion are
same. Separate digital, analog, and other grounds with a
single point connection is done for same reason that
motherboard's logic ground is isolated from chassis ground.
Provided were examples, underlying technical concepts, and
simple experiments that demonstrate the problem. Deny it all
you want - without posting a single technical fact. Intuitive
reasoning without years of engineering training and experience
means junk science reasoning. But then, David, we have dealt
with your junk science claims previously. Without a technical
reason why, the denial is only a 'junk science' response.

So that external transient currents do not pass through the
logic ground (cause computer crashes), that logic ground must
make only one connection to the chassis ground. This single
point grounding technique - done for same reasons to eliminate
ground loops in stereo systems - makes a more reliable
computer.

David Maynard wrote:
> That's a typical analog single point circuit ground, the primary purpose
> being to isolate the analog section from the digital section's switching
> induced ground noise; which has nothing to do with chassis/motherboard
> shield grounding.
>
> It is intuitively obvious to even the most casual observer, however,
> that a 9.6 inch by 9.6 inch ground planed mATX motherboard does not
> present a 'single point ground' to it's components. The point being,
> while a 'single point ground' has specific uses, to then go dancing
> around claiming it's 'the solution' to everything under the sun is
> to not understand it.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

alt.computerhardware.science-PSU

<<<<<<snore>>>>>>>>>>


"

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Motherboards are designed for numerous configurations. Some
configurations may want single point ground located
elsewhere. Some configurations may attach the entire
motherboard to chassis plate, and insulate chassis plate so
that single point ground is between chassis plate and
chassis. Furthermore, all mounting holes must be plated
through. Computer assembler is expected to bring basic
electrical knowledge to the assembly. He - not the
motherboard manufacturer - decides where the single point
ground will be made. Motherboard manufacture makes products
with numerous options. Computer assembler decides how to
implement those options.

Cross talk and other problems are why computer boards are
multi-layer assemblies using a copper plane for ground and
other planes for Vcc. Same problems also why Intel (not the
PC board designer) defines exact copper layout for PC traces
to CPU. The layout is that critical. Electronic nature even
of copper is but one reason why a CPU power supply is adjacent
to the CPU and why newer ATX power supplies have a second
power cable.

Measure the conductivity between too ends of that
motherboard ground plane. To meter, DC voltage is a perfect
short. In reality, electric currents are RF electricity. No
copper - even the ground plane - is a perfect conductor. All
copper has significant impedance. Impedance (not resistance)
is why Intel provides a layout for connections to their CPUs.
Impedance is why bypass capacitors are scattered all over the
motherboard. Conductors are electronic components when
discussing RF currents to computers and in external generated
transients. RF is why copper is not truly conductive.

If copper were truly conductive, then antennas would not
transmit and receive. Best antennas have near zero resistance
and a specific impedance. The impedance (not resistance)
makes multiple grounding of a motherboard problematic. Just
another reason why grounds are at a single point.

All conductors are electronic components. As Gary notes:
> ... at the frequencies modern computer systems operate at they
> have to use multiple grounds otherwise the systems become
> inoperable/unreliable because of cross talk.

Problems are not just limited cross talk. Cross talk alone
is not the reason for all those bypass capacitors. All PC
traces and even the PC board ground plane are electronic
components. Some currents (ie static electricity) through a
ground plane can cause catastrophic consequences especially in
hospital equipment. All grounds must be interconnected. So
again, the interconnections between various grounds use the
single point concept. Hospitals take the concept even one
step farther. Hospitals do single point grounding on a room
and on a building wide level.

Bottom line for computer assemblers who learn new tricks - a
single point connection between motherboard and chassis plate
is best adjacent to IO slots and power connection. This post
demonstrates another technical reason why: all conductors are
electronic components; especially when dealing with RF
frequencies in computers and in static electric discharges.
Just another reason why more reliable computers uses the
single point grounding technique.

"We never did that before. Therefore we don't have to do
that." People with this mentality need not reply. Unlike
other posts that disagree, these posts technically explain
why, provide examples, and provide experiments to demonstrate
the problem. IOW these posts are based upon the science and
not upon the myths so common among computer assemblers. These
posts are for those who keep learning new techniques. Single
point grounding of motherboard to chassis is the preferred
mounting method. Provided here is but another reason why: RF
currents make copper an electronic component. The relevant
parameter is impedance.

Gary wrote:
I read the article and it mainly deals with analog devices
and/or A/D
> converters and low frequency PIC chips. While it is true that multiple
> grounds can create ground loops creating hum in audio or telephone
> circuits we're dealing with radio frequencies in the hundreds of
> megahertz for the system bus / memory and in the gigahertz region in
> the case of the processor.
>
> What the article didn't address and is more of a concern to
> motherboard manufacturers is cross talk. One example of cross talk is
> noise from one set of data / memory lines at 100/133/400 megahertz
> bleeding over onto another set of data / memory lines. In computer
> circuitry this is disastrous. What may be a ground at DC or in low
> level audio or radio circuits can be a great antenna for radiating
> noise at 100+ megahertz. I'm an amateur radio licensee and I've got an
> antenna that's at DC ground potential. If you measured the resistance
> between the two leads to it, its a dead short and would be a short
> even up to the range of several megahertz. But if is a great antenna
> at 144 thru 148 Megahertz. ( Our 2 meter VHF band )
>
> I've gone over this years ago with another person and I did a search
> and found a web site of a computerized medical equipment manufacturer
> ( not too much room for error there ) and they stated just what I
> have above and that is at the frequencies modern computer systems
> operate at they have to use multiple grounds otherwise the systems
> become inoperable/unreliable because of cross talk. The late 70's era
> Radio Shack Model 1's expansion interface was a classic example of
> cross talk. It was housed in a plastic case and radiated almost as
> much cross talk inducing noise as a radio station and was notoriously
> unstable. It only ran at around 1 megahertz if memory serves me
> correctly.
>
> You'd also have to ask yourself if motherboard manufacturers didn't
> want the motherboards to be grounded to the brass standoffs why do
> they conveniently put a couple of soldered circles right in the exact
> spot where those standoffs are ? As an experiment you can take and
> attach the power leads part way onto the motherboard ( so the tips of
> your ohmmeter can connect to the metal surfaces ), then take an
> ohmmeter and measure the resistance between those soldered circles and
> the ground wires and you'll find that it's a dead short, at least it
> was on any motherboard I've ever checked.
>
> HTH
>
> Gary

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

"JAD" <Hrhackthespam@witchiepoo.broom> wrote:

>alt.computerhardware.science-PSU
><<<<<<snore>>>>>>>>>>

It's not that complicated. It goes something like this.

.... The biggest maker of computer cases includes a lot of accessories
but no insulating washers.

.... Asus, Microstar International, and other mainboard makers include
a lot of accessories but no insulating washers.

.... Mainboards include solder coated electricity conductive rings on
their mounting holes.

.... Those mounting holes are connected directly to mainboard device
ground pins. You can tell this by using a continuity checker or a
simple ohm meter.

.... All of the above circumstances lead to one conclusion. Computer
assemblers and home computer builders are going to short mainboard
device ground to the case.

.... Neither case manufacturers nor mainboard manufacturers warn their
customers about doing so.

.... Taking into consideration all of the above facts, the conclusion
is obvious (at least to me).

.... Most modern mainboards are designed to be grounded to the
computer case at their mounting holes.

You can tell them by the fact that they have electricity conductive
mounting holes. A conductor is there to conduct electricity, not to
insulate something.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

the only boards I have seen that had no ground rings and had traces
anywhere near the mounting holes was a 8086.

"John Doe" <jdoe@usenet.is.the.real.thing> wrote in message
news:Xns95ACD9695EBF6wisdomfolly@151.164.30.42...
> "JAD" <Hrhackthespam@witchiepoo.broom> wrote:
>
> >alt.computerhardware.science-PSU
> ><<<<<<snore>>>>>>>>>>
>
> It's not that complicated. It goes something like this.
>
> ... The biggest maker of computer cases includes a lot of
accessories
> but no insulating washers.
>
> ... Asus, Microstar International, and other mainboard makers
include
> a lot of accessories but no insulating washers.
>
> ... Mainboards include solder coated electricity conductive rings on
> their mounting holes.
>
> ... Those mounting holes are connected directly to mainboard device
> ground pins. You can tell this by using a continuity checker or a
> simple ohm meter.
>
> ... All of the above circumstances lead to one conclusion. Computer
> assemblers and home computer builders are going to short mainboard
> device ground to the case.
>
> ... Neither case manufacturers nor mainboard manufacturers warn
their
> customers about doing so.
>
> ... Taking into consideration all of the above facts, the conclusion
> is obvious (at least to me).
>
> ... Most modern mainboards are designed to be grounded to the
> computer case at their mounting holes.
>
> You can tell them by the fact that they have electricity conductive
> mounting holes. A conductor is there to conduct electricity, not to
> insulate something.
>
>
>
>
>
>
>
>
>
>
>
>

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

w_tom wrote:

> Grounding concepts in that cited microchip discussion are
> same.

No, they are not 'the same', and that you think they are belies your lack
of understanding of it.

> Separate digital, analog, and other grounds with a
> single point connection is done for same reason that
> motherboard's logic ground is isolated from chassis ground.
> Provided were examples, underlying technical concepts, and
> simple experiments that demonstrate the problem.

What you 'provided' was a pile of B.S.

> Deny it all
> you want - without posting a single technical fact.

I gave you, among other things, the reason for the separate analog ground
and also explained the problem 'single point ground' has with frequencies
over 1 Mhz, but, as usual, you snip out what you then claim wasn't given.

> Intuitive
> reasoning without years of engineering training and experience
> means junk science reasoning.

Describing yourself again, I see.

> But then, David, we have dealt
> with your junk science claims previously.

I suppose that means you still haven't figured out that surge protection
which keeps every external connection to the computer at the same potential
protects the internals.

> Without a technical
> reason why, the denial is only a 'junk science' response.

You are the biggest purveyor of 'junk science' I've run across in a long
time, but you win the pompous A-hole category hands down.


> So that external transient currents do not pass through the
> logic ground (cause computer crashes), that logic ground must
> make only one connection to the chassis ground.

Since you want to concentrate solely on 'external transients', an 'external
transient' has only two ways to get into the computer. One would be through
the grounded case, an impossibility (if it's properly designed). The other
is via an external device (or power) connection and what you want to do is
shunt that to case as soon as possible rather than have it traverse through
the whole system seeking your beloved 'single point ground'.

Look up Intel 29835002.pdf, Intel® 815E Chipset Platform Design Guide,
section 2.2 Electrostatic Discharge Platform Recommendations where it
specifies connecting *two* motherboard mounting holes to ground, one on
each side of the rear I/O area, so that any ESD there is shunted to case in
the shortest possible path.


> This single
> point grounding technique - done for same reasons to eliminate
> ground loops in stereo systems - makes a more reliable
> computer.

'Hum' in an audio system is not an external ESD transient nor is it above 1
Mhz. It is, however, another example of how you take something completely
unrelated and misapply it with your B.S. 'examples'.

>
> David Maynard wrote:
>
>>That's a typical analog single point circuit ground, the primary purpose
>>being to isolate the analog section from the digital section's switching
>>induced ground noise; which has nothing to do with chassis/motherboard
>>shield grounding.
>>
>>It is intuitively obvious to even the most casual observer, however,
>>that a 9.6 inch by 9.6 inch ground planed mATX motherboard does not
>>present a 'single point ground' to it's components. The point being,
>>while a 'single point ground' has specific uses, to then go dancing
>>around claiming it's 'the solution' to everything under the sun is
>>to not understand it.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

David Maynard provides an Intel example of the single point
ground technique. Intel recommends two screws at the far end
of a motherboard so that, again, electrical currents in the
chassis do not pass through motherboard logic ground. The
single point ground, IO board connections, and power input
connect to chassis at the same single point - at the far end
of a motherboard. Where I recommended only one screw
connection, Intel recommends two in the same location to
create the single point ground at the farthest edge of
motherboard.

Demonstrated by page 30 of that Intel 815E Chipset Platform
document, no currents across electronic sections of
motherboard means no computer crashes due to static electric
discharges to chassis. Best not to mount motherboard with
conductive connections everywhere. Intel recommends only two
connection, both at the far edge to make same single point
ground - adjacent to IO slots and power connector. Intel
document does not recommend conductive standoffs everywhere on
motherboard - as I had posted.

David Maynard wrote:
> ...
> Look up Intel 29835002.pdf, Intel® 815E Chipset Platform Design Guide,
> section 2.2 Electrostatic Discharge Platform Recommendations where it
> specifies connecting *two* motherboard mounting holes to ground, one
> on each side of the rear I/O area, so that any ESD there is shunted to
> case in the shortest possible path.
> ...

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

As noted previously, motherboards would be manufactured for
many other configurations. But Intel 29835002.pdf recommends
only making a motherboard logic ground connection at far end,
and adjacent to other devices that also make a chassis ground
connection - IO peripheral cards.

Intel design guidelines recommend 'single point ground'
mounting via two mounting screws adjacent to IO card slots.
Intel guidelines also demonstrate that other mounting holes
not make an electrical chassis connection. Furthermore, note
extra grounding layers that Intel recommends in the single
point region for reducing ESD (chassis) noise into logic
ground.

Motherboard is best mounted using a single point ground
connection.

It was always good pc board practice to line every mounting
hole with copper feedthroughs. This does not mean all
mounting holes need or should make a connection to other
grounds. Those plated feedthroughs mechanically strengthen
each mounting hole. But Intel only recommends that two holes
make an electrically conductive connection to chassis.
Reasons why have been posted previously.

JAD wrote:
> um if this is the case, what are MB manufactures trying to do? By
> putting ground rings around each mount hole(on both sides in some
> cases), they are in fact saying this point needs to be grounded. If
> they did not want a ground point there, the ring should be non
> conductive. Makes little sense and To point out 1 single scenario on
> one particular board, and if it was DM stating it, knowing him he
> probably stayed up all night finding the one 1 single situation that
> supports whatever his point is.

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Actually one screw to chassis is a single point just as two
screws were a single point. The single point was the entire
region that included IO slots, single screw to chassis, and
power supply connection. This single point (or region) is
located at the far end of PC board to that no transient
current passes through sensitive electronics regions.

Again I emphasis an Intel recommendation that the single
point area have additional grounding layers. Just more reason
for any ESD currents to remain in the single point region and
not taken scenic tours through the sensitive digital
electronic areas.

I noted an Intel suggestion of more grounding at the chassis
connection area. I did not bother to explain why while
wondering if you understood the significance of that
additional motherboard grounding. I guess not.

Intel demonstrates single point grounding. This so that
transient currents in chassis do not pass across logic ground
plane where transients could cause computer crashes. Computer
assemblers are advised to heed Intel recommendations. Do not
connect motherboard to chassis at every mounting point - to
increase computer reliability. A technique long practiced by
experienced and learned engineers. A practice that many
computer assemblers still deny - even after an Intel *pdf
document demonstrates the concept.

Again it is a so simple concept. Connect logic ground to
chassis ground so that transient current on chassis will not
pass through motherboard. It is called a single point
ground. It is even demonstrated by the cited Intel document
that YOU provided. I must assume you did not comprehend what
Intel wrote. For some, the complexities of grounding were
previously unknown. Grounding is but another reason why ESD
solutions can appear complex.

BTW I did not say "that only ONE is the only suitable
means". Read back. I posted other means of obtaining the
single point ground. Another was to connect every mounting
hole the a chassis plate, and then have only one electrical
connection from chassis plate to chassis. Why did you forget
this and other single point grounding solutions? Is being
wrong (again) so hard to admit?

We keep doing this. I provide facts and electrical
concepts. You keep denying it; all without demonstrating
knowledge of engineering principles. This time it is more
interesting. You provided the Intel document that
demonstrates what I had posted. Interesting new way to deny
basic electrical principles. Deny them and then cite an Intel
document that disagrees with your denial. Yes, I am amused.

David Maynard wrote:
> It is not at the 'far end'. They are as near the potential ESD
> entry point as possible but HALF way across the motherboard, over
> 6 inches, from each other.
>
>> of a motherboard so that, again, electrical currents in the
>> chassis do not pass through motherboard logic ground. The
>> single point ground, IO board connections, and power input
>> connect to chassis at the same single point - at the far end
>> of a motherboard. Where I recommended only one screw
>> connection, Intel recommends two in the same location to
>> create the single point ground at the farthest edge of
>> motherboard.
>
> "Two" is not a "single point."
>
>> Demonstrated by page 30 of that Intel 815E Chipset Platform
>> document, no currents across electronic sections
>
> Correct, because they are shunted to chassis *there* instead of
> seeking your 'single point ground'.
>
> The motherboard ground also transverses the PSU power cable to the
> PSU's chassis ground; which makes for THREE chassis ground points
> in just this limited example.
>
> And then, each AGP/PCI card with I/O will have it's chassis end
> plate connected to ground. And then there's the drives which have
> logic to chassis ground connections. There's logic/chassis ground
> connections all OVER the place.
>
> > of
> > motherboard means no computer crashes due to static electric
> > discharges to chassis. Best not to mount motherboard with
> > conductive connections everywhere. Intel recommends only two
> > connection, both at the far edge to make same single point
> > ground - adjacent to IO slots and power connector. Intel
> > document does not recommend conductive standoffs everywhere on
> > motherboard - as I had posted.
>
> The issue was not about a connection 'everywhere'. The issue was your
> patently false claim that only ONE is the only suitable means.
>
> >
> > David Maynard wrote:
> >
> >>...
> >>Look up Intel 29835002.pdf, Intel® 815E Chipset Platform Design Guide,
> >>section 2.2 Electrostatic Discharge Platform Recommendations where it
> >>specifies connecting *two* motherboard mounting holes to ground, one
> >>on each side of the rear I/O area, so that any ESD there is shunted to
> >>case in the shortest possible path.
> >>...

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

On Thu, 25 Nov 2004 20:01:08 -0500, w_tom <w_tom1@hotmail.com> wrote:

> Motherboards are designed for numerous configurations. Some
>configurations may want single point ground located
>elsewhere. Some configurations may attach the entire
>motherboard to chassis plate, and insulate chassis plate so
>that single point ground is between chassis plate and
>chassis. Furthermore, all mounting holes must be plated
>through. Computer assembler is expected to bring basic
>electrical knowledge to the assembly. He - not the
>motherboard manufacturer - decides where the single point
>ground will be made. Motherboard manufacture makes products
>with numerous options. Computer assembler decides how to
>implement those options.
>
> Cross talk and other problems are why computer boards are
>multi-layer assemblies using a copper plane for ground and
>other planes for Vcc. Same problems also why Intel (not the
>PC board designer) defines exact copper layout for PC traces
>to CPU. The layout is that critical. Electronic nature even
>of copper is but one reason why a CPU power supply is adjacent
>to the CPU and why newer ATX power supplies have a second
>power cable.
>
> Measure the conductivity between too ends of that
>motherboard ground plane. To meter, DC voltage is a perfect
>short. In reality, electric currents are RF electricity. No
>copper - even the ground plane - is a perfect conductor. All
>copper has significant impedance. Impedance (not resistance)
>is why Intel provides a layout for connections to their CPUs.
>Impedance is why bypass capacitors are scattered all over the
>motherboard. Conductors are electronic components when
>discussing RF currents to computers and in external generated
>transients. RF is why copper is not truly conductive.
>
> If copper were truly conductive, then antennas would not
>transmit and receive. Best antennas have near zero resistance
>and a specific impedance. The impedance (not resistance)
>makes multiple grounding of a motherboard problematic. Just
>another reason why grounds are at a single point.
>
> All conductors are electronic components. As Gary notes:
>> ... at the frequencies modern computer systems operate at they
>> have to use multiple grounds otherwise the systems become
>> inoperable/unreliable because of cross talk.
>
> Problems are not just limited cross talk. Cross talk alone
>is not the reason for all those bypass capacitors. All PC
>traces and even the PC board ground plane are electronic
>components. Some currents (ie static electricity) through a
>ground plane can cause catastrophic consequences especially in
>hospital equipment. All grounds must be interconnected. So
>again, the interconnections between various grounds use the
>single point concept. Hospitals take the concept even one
>step farther. Hospitals do single point grounding on a room
>and on a building wide level.
>
> Bottom line for computer assemblers who learn new tricks - a
>single point connection between motherboard and chassis plate
>is best adjacent to IO slots and power connection. This post
>demonstrates another technical reason why: all conductors are
>electronic components; especially when dealing with RF
>frequencies in computers and in static electric discharges.
>Just another reason why more reliable computers uses the
>single point grounding technique.
>
> "We never did that before. Therefore we don't have to do
>that." People with this mentality need not reply. Unlike
>other posts that disagree, these posts technically explain
>why, provide examples, and provide experiments to demonstrate
>the problem. IOW these posts are based upon the science and
>not upon the myths so common among computer assemblers. These
>posts are for those who keep learning new techniques. Single
>point grounding of motherboard to chassis is the preferred
>mounting method. Provided here is but another reason why: RF
>currents make copper an electronic component. The relevant
>parameter is impedance.

Here's a URL from *NASA* at the Marshall space flight center regarding
the use of single point VS multiple point grounding and they show the
frequency cutoff regions between single point and multiple point
grounding. Scroll down to figure 4.

http://klabs.org/DEI/References/de [...] 14msfc.pdf

With a 1 foot ground plane at frequencies up to 3 MHz they recommend
single point grounding. With the same size ground plane up to 10 MHz
they recommend hybrid grounds, At frequencies at and above 30 MHz
they recommend multiple point grounds.

I've got an amateur radio transceiver about the size of a bible that
on transmit puts out 55 watts of power on our 2 meter VHF band ( 144 -
148 megahertz ) It'll also receive from 136 to 174 megahertz. The
receive section is a double conversion super heterodyne with a first
intermediate frequency of 15 megahertz and a 2nd intermediate
frequency of 450 Kilohertz. It's synthesized with most likely a phase
locked loop. With that amount of power and the frequency conversion
sections It's no doubt got all kinds of RF potentially floating around
inside. Recently it developed a popping sound through the speaker on
transmit and some of the radios also had the popping sound on their
transmitted audio. I did a search on one of the Yahoo groups
concerning this particular radio and some of the them had left the
factory without the grounding screws being sufficiently tightened. The
cure was easy. According to the instructions you merely had to loosen
the eight *grounding* screws on the circuit board and retighten them
nice and snug so that they made a good ground contact and maybe even
use some star washers for extra good grounding. I just loosened the
eight screws, then tightened them nice and snug ( eight grounding
points ) and the popping noise went away.

Now this is a commercially constructed radio from one of ham radio's
premier brands ( Icom ) and they had *eight* grounding points from
the circuit board to chassis ground.

I'm not going to get into a real lengthy debate as if you want to use
just one ground point on your mother board feel free to do so, But
when I see and use commercially built equipment that has to deal with
all kinds of radio frequencies potentially floating around inside
using multiple ground points and see soldered through holes on
computer motherboards that have ground traces connected to them and
brass stand offs that match the location of the grounded circles it
seems painfully obvious that the motherboard manufacturer intended for
those soldered circle to be connected to ground.

Someone *has* to make a *conscious* effort to run a ground trace to
those soldered circles. If they were just there for support of the
motherboard they could easily just leave the ground trace off of it.

You can have the last word as you seem steeped in the concept that
single point grounding is the cure all concept covering every device
that operates from direct current to the frequency of light.

Single point grounding does have its place but when it comes to radio
frequencies in the hundreds of megahertz + , you're dealing with an
entirely different animal than direct current or low frequency RF.


Gary



>
>Gary wrote:
> I read the article and it mainly deals with analog devices
>and/or A/D
>> converters and low frequency PIC chips. While it is true that multiple
>> grounds can create ground loops creating hum in audio or telephone
>> circuits we're dealing with radio frequencies in the hundreds of
>> megahertz for the system bus / memory and in the gigahertz region in
>> the case of the processor.
>>
>> What the article didn't address and is more of a concern to
>> motherboard manufacturers is cross talk. One example of cross talk is
>> noise from one set of data / memory lines at 100/133/400 megahertz
>> bleeding over onto another set of data / memory lines. In computer
>> circuitry this is disastrous. What may be a ground at DC or in low
>> level audio or radio circuits can be a great antenna for radiating
>> noise at 100+ megahertz. I'm an amateur radio licensee and I've got an
>> antenna that's at DC ground potential. If you measured the resistance
>> between the two leads to it, its a dead short and would be a short
>> even up to the range of several megahertz. But if is a great antenna
>> at 144 thru 148 Megahertz. ( Our 2 meter VHF band )
>>
>> I've gone over this years ago with another person and I did a search
>> and found a web site of a computerized medical equipment manufacturer
>> ( not too much room for error there ) and they stated just what I
>> have above and that is at the frequencies modern computer systems
>> operate at they have to use multiple grounds otherwise the systems
>> become inoperable/unreliable because of cross talk. The late 70's era
>> Radio Shack Model 1's expansion interface was a classic example of
>> cross talk. It was housed in a plastic case and radiated almost as
>> much cross talk inducing noise as a radio station and was notoriously
>> unstable. It only ran at around 1 megahertz if memory serves me
>> correctly.
>>
>> You'd also have to ask yourself if motherboard manufacturers didn't
>> want the motherboards to be grounded to the brass standoffs why do
>> they conveniently put a couple of soldered circles right in the exact
>> spot where those standoffs are ? As an experiment you can take and
>> attach the power leads part way onto the motherboard ( so the tips of
>> your ohmmeter can connect to the metal surfaces ), then take an
>> ohmmeter and measure the resistance between those soldered circles and
>> the ground wires and you'll find that it's a dead short, at least it
>> was on any motherboard I've ever checked.
>>
>> HTH
>>
>> Gary