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PC Power Supply Discussion Troubleshooting and discussion of computer power supplies

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  #1  
Old 07-24-2007
Skyguy Skyguy is offline
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Default Kill-A-Watt numbers seem low....?

Wanted to measure the power draw of my system, so I bought a Kill-A-Watt digital meter as recommended by Jonny. Awesome, seems to work fine. Except my numbers seem rather "low" in my opinion. I would think the power draw would be higher. Here's the full system specs:

-C2D 6300 OC'd to 3.2ghz
-Gigabyte 965P-DS3 mobo
-2 gigs DDR2
-2 IDE optical drives
-3 SATA hard drives (250 gb each)
-8800 GTS 640
-Swiftech 3/8" water cooling loop (w/MCP355 pump)
-5 - 120mm Noctua fans @ 1200 rpm (running at 12v)
-Zalman fan controller
-Seasonic Energy Plus 650w PSU
-G15 keyboard, MX518 optical mouse

Kill-A-Watt is plugged directly into wall, computer plugged directly into Kill-A-Watt.

Now, I measured the wattage at idle, with dual Prime95 instances load, and also with 3DMark06 running as well.

Absolute highest draw I could measure is about 300w, system CPU and graphics card at full load. That seems low. Would there be something causing a drop in the "readable" power? Or does that number seem about right?

Is there any way I can verify the Kill-A-Watt is getting the right numbers?

I always thought a system with specs like this would draw somewhere in the neighborhood of 450-500w for sure. If this system only draws 300w, then why would anyone ever need 700-100w? Even SLI/Crossfire wouldn't suck anywhere near that much juice. Am I missing something?


Thanks in advance of any help.
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Old 07-24-2007
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Sounds about right to me.
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Old 07-24-2007
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Per Hansson Per Hansson is offline
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Sounds right, remember to multiply that numer with the efficiency of your PSU

Most PSU's are 80% efficient or thereabout so: 300w X 0.8 = 240w DC power usage

You might be interested in my thread here on comps power usage (hope it's ok to flash my thread here Johnny?)

http://www.badcaps.net/forum/showthread.php?t=4024
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Old 07-24-2007
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Quote:
Originally Posted by Skyguy View Post
Absolute highest draw I could measure is about 300w, system CPU and graphics card at full load. That seems low. Would there be something causing a drop in the "readable" power? Or does that number seem about right?
Not saying it is wrong in this case but in general yes.

I have had a number of power supplies that for one reason or another the Kill-A-Watt would give me AC inputs at or below the DC output. I don't know why and noone who has responded to my questions about it has ever come up with an answer. Good news for me is I had already aquired a better power meter when I started hitting the really funky things with the Kill-A-Watt.
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Old 07-24-2007
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Same here. Now run Orthos and the Performance Test in Company of Heroes and you may be able to push it to 320-330.

You have to be aware that 3DMark06 does not push your graphics card as much as some games out there do. I have done ALOT of testing to see what programs consume the most graphics power and Lost Planet and CoH take the crown in DX9 mode. ATITool's spinning box comes a close third with 3DMark06 sitting behind Medieval II: Total War and the World in Conflict demo.
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Old 07-24-2007
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Quote:
Originally Posted by Skyguy View Post
I always thought a system with specs like this would draw somewhere in the neighborhood of 450-500w for sure. If this system only draws 300w, then why would anyone ever need 700-100w? Even SLI/Crossfire wouldn't suck anywhere near that much juice. Am I missing something?
Welcome in real world. You see the light.

Yep, your consumption seems right. And real. Nothing to worry.
I'm a 400W PSU guy here so maybe others will explain you why a 700W PSU is needed for a Quad with GTX/R600.
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Old 07-24-2007
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Quote:
Originally Posted by burebista View Post
....maybe others will explain you why a 700W PSU is needed for a Quad with GTX/R600.
Why do we keep going back to this argument? I really need to write that article.

Because in some cases, you can get a better 700W than some 400W. There isn't one PSU that's right for everyone, so the 400W that's right for you isn't necessarily something someone else would like/want.

Also, I still say that I'm not going to endorse running a PSU at 75% of it's total capability for the long haul.
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Old 07-24-2007
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Run that Quad core and your HD2900XT clocked sky high on your average 400W unit and come back to me after a few months. The HD2900XT is a beast. Somebody on OCF (can't take names as certain ES issues may be involved), runs an X6800 and 2900XT's CF on extreme cooling. He tripped the OCP on the 12V line of a Zippy 700W. Note that this 700W unit powers ONLY the GPU and HDD's to alleviate cross-load issues. He's using a Sparkle 550 for the CPU.

You may say CF=! single card etc, but these modern cards are hogs and I will not run with some generic 450W.
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Old 07-24-2007
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Haha, no, it's a wonder anything runs fine on the generic "XXXw" PSU's

I say that is a feat of engineer if anything (for the rest of the components in the system that is!)
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Old 07-24-2007
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I don't even think it's a matter of cheap vs. good quality. I think there's a number of people that are getting 400W and 500W power supplies for G80 GPU based machines that are going to be in for a surprise a year from now.
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