1:1 FSB : Ram ratio. Is it necessary for Q9550? - CPU & Components
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 Thread : 1:1 FSB : Ram ratio. Is it necessary for Q9550?
 
hohyss
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n°1849822
08-13-2008 at 06:42:46 PM

Hello everyone. This is my first post at toms hardware.

I am currently trying to get Q9550 Yorkfield and 8GB of RAM ( ddr 6400 ).

I;ve heard that 1:1 ratio is necessary to maximize your performance.

I have few questions regarding this issue.


1. When not overclocking

FSB of Q9550 at the stock setting ( I believe its around 333mhz )
is not equal to ddr 6400 ( 400mhz)

Do I have to adjust the fsb or ram to make it equal to 1:1 despite the
fact that im not overclocking it?


2. When Overclocking

Ive seen some post where people have 4:5 ratio or 5:4. What will be the performance difference for not having 1:1 ratio? 20%-40%?
Is 1:1 ratio really necessary?

3. Is Q9550 capable for OC?

Im not sure whether q9550 is a good cpu for overclocking. Looks like I have to go all the way up to 400mhz ( 3.4ghz). Is it possible on stock cooler or should I get an aftermarket cooler like arctic freezer 7 pro?

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jimmysmitty
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n°1849824
08-13-2008 at 06:56:17 PM

A 1:1 ratio is optimal for stability. Right now it would be at 667MHz for a 1:1. But if you go to say a 800MHz memory you will run it at a higher ratio and that normally allows for a bit better performance at the loss of stability.


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sportsfanboy
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n°1849827
08-13-2008 at 07:03:47 PM

There's lots of reasons for running 1:1... One is less stress on the motherboard because it doesn't have to deal with dividers. Two is generally lower latency, because when you go through a divider, you take a memory performance hit, but I don't think it is 20 to 40%. For example, no one with ddr3 1333 ram , are running 1:1. You would need a fsb of 666mhz, just isn't achievable with today's hardware. I wouldn't worry about getting 1:1, if you do great, if not, don't worry about it.

What I like to do is play around with frequency, timings, and dividers, until I get the lowest memory latency in Everest.

Optimizing an overall overclock, and particularly the memory, is all about settings, than testing the settings for stability and speed.

That cpu can make it to 3.4 no problem on a decent mobo, however the temperatures may be a little high with stock cooler.


Message edited by sportsfanboy on 08-13-2008 at 07:10:21 PM
Vertigon
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n°1849830
08-13-2008 at 07:23:00 PM

"For example, no one with ddr3 1333 ramhttp://en.wikipedia.org/wiki/Ram , are running 1:1. You would need a fsbhttp://en.wikipedia.org/wiki/FSB of 666mhz, just isn't achievable with today's hardware."

huh?

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jimmysmitty
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n°1849832
08-13-2008 at 07:28:38 PM

^Thtas funny considering Iam runnin a 1:1 FSB with my memory on a 333MHz FSB x 4 @ 1333MHz. And CPU-Z states it too.

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Vertigon
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n°1849835
08-13-2008 at 07:32:44 PM

That's impossible jimmy, sportsfanboy said so lol

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uguv
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n°1849836
08-13-2008 at 07:32:53 PM

Yeah but that just means your ram is running at DDR2 667 speeds. He said nobody runs ram at 1333 speeds at 1:1 because it would take a 667mhz FSB.

sportsfanboy
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n°1849840
08-13-2008 at 07:39:21 PM

Guys, DDR2 800mhz requires a fsb of 400mhz to get 1:1!

DDR2 1000mhz requires a fsb of 500mhz to run 1:1!

DDR2 1200mhz requires a fsb of 600mhz to run 1:1!

DDR3 1333mhz requires a fsb of 666 to run 1:1!

Get your head out of your azzes before giving me crap, I'm right

Message quoted 1 times
Message edited by sportsfanboy on 08-13-2008 at 07:40:53 PM
Grimmy
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n°1849842
08-13-2008 at 07:40:38 PM

Um.. the missing key word is rated fsb. :P

hohyss
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n°1849843
08-13-2008 at 07:41:55 PM

So I guess I should go with Q9550 and ddr 6400 ( ddr 800mhz ) +Artic cooling freezer 7 pro ( just to be safe )
then overclock it all the way to 3.4 gbz so i can have 1:1 ratio with ddr 800

I hope this combination is good. And btw I don't have to buy any thermal compound since artic cooling freezer 7 pro comes with preapplied grease. Right?

Message quoted 1 times
Grimmy
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n°1849844
08-13-2008 at 07:42:24 PM

sportsfanboy wrote :

Guys, DDR2 800mhz requires a fsb of 400mhz to get 1:1!

DDR2 1000mhz requires a fsb of 500mhz to run 1:1!

DDR2 1200mhz requires a fsb of 600mhz to run 1:1!

DDR3 1333mhz requires a fsb of 666 to run 1:1!

Get your head out of your azzes before giving me crap, I'm right



Heh... I remember thinking the same thing.

Well, you can still run DDR800 at 533 for a 1:1 ratio. But for argument sake, yes @ advertised speed.

uguv
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n°1849849
08-13-2008 at 07:51:25 PM

hohyss wrote :

So I guess I should go with Q9550 and ddr 6400 ( ddr 800mhz ) +Artic cooling freezer 7 pro ( just to be safe )
then overclock it all the way to 3.4 gbz so i can have 1:1 ratio with ddr 800

I hope this combination is good. And btw I don't have to buy any thermal compound since artic cooling freezer 7 pro comes with preapplied grease. Right?



Well you have a few options:

1) You could leave the processor at stock speeds and by default your ram will run at DDR2 667 speeds. This wouldn't be the end of the world if you're not comfortable overclocking.

2) You could change the ratio and run your ram at DDR2 800 speeds but leave the processor at its stock speed. I probably wouldn't bother with this since if you're already messing around in the BIOS you might as well overclock the processor. ;)

3) Do as you say and overclock the processor so that it uses a 400mhz (x4) fsb. This would allow the ram to run at DDR2 800 with a 1:1 ratio.

4) Overclock the processor as far as you can and overclock the ram as well.

Personally I'd go with option 1 or 3.

Edit: nice info there, Computronix. I swear your post was originally above mine but moved somehow!


Message edited by uguv on 08-13-2008 at 08:00:13 PM
sportsfanboy
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n°1849850
08-13-2008 at 07:52:50 PM

You can Grimmy, but I think the op was talking about maximizing his ram and trying for a 1:1 ratio without having to down clock his ram.

I always thought true 1:1 meant: FSB frequency x 2 = rams rated speed. So ddr2 800mhz should be 400mhz.

But you can run your system slower without a divider, however I believe the performance hit of seriously under clocking the ram, is greater than running it at full speed using a divider.

CompuTronix
Tenacity & Attention to Detail
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n°1849851
08-13-2008 at 07:54:57 PM

Guys,

 

I posted the following on an earlier thread - http://www.tomshardware.com/forum/ [...] o#t1765557

 


Quote :

 

Ah, but wait... there's more! :pt1cable: Let's consider some of the additional variables involved in the memory big picture: :o

 

A ratio of 1:1 provides the best level of stability, since the memory controller, which is an integral part of the northbridge chipset for Intel processors, does not need to translate data flow across the FSB between the memory modules and the processor(s). Also, since memory and processor FSB clocks are synchronous at 1:1, (400:400 or DDR 800), there is no additional latency introduced.

 

If a minimal ratio of 4:5 (400:500 or DDR 1000) is used, then the resulting increase in memory frequency is effectivey cancelled out by the latency introduced in translation across the FSB between memory and processor clocks, and no increase in memory performance can be noticably detected in benchmarks. Also, asynchronous or mismatched clocks, create an element of potential instability within the memory controller, so depending on the chipset, an increase in northbridge and memory voltage is required for stability, which results in more heat, and less FSB overclock ceiling.

 

If a more aggressive ratio of 2:3 (400:600 or DDR 1200) is used, then the increase in memory frequency can marginally overcome the latency introduced in translation across the FSB between memory and processor clocks, resulting in a marginal increase in memory performance, which typically yields an increase in memory benchmarks of 2 to 3%, and is relatively negligible in terms of overall system performance.

 

In the case of expensive DDR3, where a ratio of 1:2 (400:800 or DDR 1600) or 2:5 (400:1000 or DDR 2000) is used, even with the tightest timings, an increase in memory benchmarks of only 3 to 4% is yielded over DDR2 800, which once again, is relatively negligible in terms of overall system performance. It's also noteworthy to consider that memory timings of 4-4-4-12 compared to 5-5-5-15, will yield an increase in memory benchmarks of less than 2%. However, for those of us who have the need for speed, we'll take whatever we can tweak.

 

Additionally, at equal specifications, 4 memory modules offer less FSB overclock ceiling than 2 modules, since more northbridge and memory voltage is required to maintain stability, and 4 slots require twice the current of 2 slots, again resulting in more heat, which typically is pulled into the CPU cooler, where it can increase processor temperatures by a few unwanted degrees.

 

I hope this helps to provides a greater degree of perspective (no pun intended). :D

 

Comp :sol:

 

Incidentally, I run my rig at 1:1.


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Q9650 @ 4.2 | Xigmatek HDT-SD964
Ambient 22c | CPU 65c | Core 70c
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sportsfanboy
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n°1849853
08-13-2008 at 08:00:31 PM

Man... I'm gonna shut up from now on, and let Computronix, do the dirty work.

Nice Comp

CompuTronix
Tenacity & Attention to Detail
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