AMD and Intel stress idle and max power use by their processors and platforms. To tell the whole story, we look at how much power typical systems consume over time, under different workloads.

http://www.tomshardware.com/2007/1 [...] index.html

Its already posted, and unfortunately, flamed.

Duh, P = E / t ... so E = P / t for constant P situations, otherwise E = Integral ( P dt), so you can decrease energy used by making the P/t fraction lower...

What I dont get is why a 570w power supply was used for a system that barely went over 200w at full load. (or barely over 150w in the intel case).

That's easy. Take AMD for example. They recommend a 550 Watt PSU with at least 35 amps for their 2600xt DDR3 series. Any questions?

Also, with a smaller amount of power being drawn from a higher wattage power supply, you get a more stable power being delivered ... in addition to the efficiency of the power supply being better (ie more of the power being drawn from the wall is actually used in the system in relation to being turned straight into heat).

Other than stable power that meets the systems needs and maximum PSU efficiency, the choice of PSU wattage isn't important for this article.

Actually a 300-350(provided it meets the needed 12 volts requirments) watt psu would have been the most efficient since power supplies hit there map efficeny at about 50% load

Corsair shows it best

depending on the psu peak efficiency happens in the 45%-55% area

And the power is no more or less stable as long as its a good psu...

I have been trying to hammer this point home forever....a GOOD psu does not need to be 1000 watts to run a modern system

My system takes at most 350 watts from the wall(and thus does not get 24/7 use....i have another system for that)

Case: Antec 900
PSU: OCZ 700watt(got for the efficiency)
Board: P35 DS3R
CPU: Q6600 @ 3.00
CPU cooling : Zalman 9500 @ 500-2200 rpms(PWM)
Memory: 2x 1024MB ,2X 512MB 667 @ 4,4,4,10 2.0 volts
Video: 8800GTX 600(core) 1400(shader) 900 x2(memory)
Storage:
2x WDC 250gig (Raid0)
2x Seagate 320gig(Storage)
2x Seagate 500gig(Storage)
Optical drive: Samsung SH-W162
TV card: PVR 250
Sound: Creative SB Audigy 2zs

That said a 2600XT does not need 35 amps. It takes under 4 amps(vs the 11 used by a 8800GTX) of 12 volt power to run. so unless you are running some super high end 4 socket setup 35 seems to be a high rating...

Interesting review. Thanks for putting it up.

Coret, your conclusion here is wrong. It is actually more efficient to have a lower total power supply because it tends to have an efficiency curve that is domed. Where the it is most efficient in the middle of its range.

Take for example the new Energy Star requirements. It make a system that meets CAT A idle = 50W you would need to use a PS that is rated at 250W or less. This would be using onboard graphics a single stick of 512MB memory and a processor that idles at or below 8W. The Energy Star requirements demand the use of an 80Plus efficient PS. The definition for this is it must be 80% from 20% loading up to 100% loading. So a Power Supply that is 250W running at 20% load is equal to the system running at 50W.

I have measured these systems in my work. If you move below the 20% loading the efficiency really drops of. So your statement that that about the efficiency of a High wattage Power supply is the opposite of what you have stated. And your other statement that about more stable power is also called into question.

Most Power Supples need a minimum loading for them to regulate accurately. If your high wattage PS is not provided with a sufficient load you could have fluctuating power delivery.

Most PS vendors provide an power to efficiency graph on their websites. If you want the best tuned system then match your power supply's most efficient output to your most typical loading.

If you build a new computer now, chances are it will have a 500W PSU or stronger, not 300W. I think they chose well, matching real life better.

That is true but to be in the PS sweet spot you would need to run your system at something other than idle. You system would need to draw about 250W. That means a either a 2900XT or a 8800GTX and a quad core processor.

This was a good review.

I regret to say that I've been saying this for a VERY long time in quite a few places. I love reading those articles where "Dr. XYZ" says "OMG AMZ R0xx0rs for efficiency". My whole take on it is really nobody can say who is more efficient than anyone else because NOBODY has ever had 2 systems run side by side in real world applications where both have to do the exact same tasks. I want to see someone set up 2 desktops/servers and have them both do the exact same work for a month straight. I'm not sure if this is even possible or feasible, but it would be cool to see. Pit an AMD and and Intel chip against each other competing for 'efficiency'.

On another note, I'm glad to see that someone actually crunched the numbers to see how much it differs. I've always thought the ultra low voltage CPUs was crap because if I wanted to do something complex, it would take me longer and could possibly negate the whole purpose for spending money on an 'efficient' processor.

Now I want to go find all those places where I said exactly what this article said and slam all those people that said 'well.. if it went like that then we'd know' and 'why don't you do it yourself and prove it to the world'.

/victory dance

All I can say is, what I said on the other thread. If you want power efficiency, don't get a high end video card.

I've done my simple test using the P3 killowatt I got a long while back. To compare my results:

My old system P4 3ghz 6800GS 450w PSU:
Idle - 110-115w
My dads new system E4300 @ 2.4ghz 7300GT 420w PSU
Idle - 107-109w
My new (screamer) E4400 @ 2.8ghz 8800GTS 620w PSU
Idle - 160-167w

So my readings are right off the PSU end. I also ran a different test, since I got new batteries for my APC 1400 UPS.

The P4 linux system ran 20 mins until it started beeping.

The E4400 XP system ran 11 mins until it started beeping.

Now I dunno about that 2900XT which has 6pin and 8pin for power, like this picture shows from newegg:

So regardless of how power efficiently a CPU maybe, its not the only part that tends to eat power.

Just my 2 pieces of copper.

Edit:

And I did try to underclock my GPU:

Default speeds - GPU@588 Memory@920

Reduced all the way - GPU@295 Memory@460

Power consumption only reflected 12watt difference changing the 2d clocks.

And is still 35watt more then my old P4.

Grimmy, what chipset does your motherboard use?

Lets see...

Asus P4PE. Chipset, Intel 845PE - my old P4 system
MSI SLI 650i nvidia - Dad's E4300
MSI Platinum 650i nvidia - My E4400

To add info for TDP

P4 3ghz - 89w
E4300 - 65w but oc 2.4ghz = 80w
E4400 - 65w but oc 2.8ghz = 84w

Edit:

speedstep enabled

E4400 - 1.6ghz idle = 50w
E4300 - 1.6ghz idle = 53w

using that PSU calculator overclock thingy.

I need to actually clip my computer(with a fluke meter that uses a lazy ass induction clip, so its easy....i am just lazy) since it will be more accurate then my UPS....