PSU for GTX480 sli + GTX280 physx?

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jbh545

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Jun 10, 2008
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I just had a card unexpectedly fall into my lap. I'm swapping my 5970+5870 setup for a pair of GTX 480s, and instead of the $350 cash I was asking for the 5870 someone gave me $300 + a 1GB 4870. The result is that the GTX 280 in my wife's PC is now free, and now I have to decide if I want to sell it or toss it in my own PC for physx.

What would be the power requirement of a monstrous system like that? I have a corsair HX1000 right now which is an excellent supply and took care of my trifire setup running the 5970 at 5870 speeds no problems. I know it would probably take care of just the 480s with a bit of room to spare, but is throwing a 280 on top of that too much? Any idea if the load power on the 280 would be less than normal since it's just doing physx?
 
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SHAQ

Senior member
Aug 5, 2002
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Original 280? IF you use it for Physx it won't use the whole 200 watts. Rarely do they go over 30% utilization in games. I think the HX1000 will handle it. So figure 600 watts plus whatever CPU you have.
 
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jbh545

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Jun 10, 2008
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Yeah, I think it's an original 280. Seems like I might be cutting it close but I dunno. 500 wats for a pair of 480s plus whatever the 280 and rest of the system use, plus a bit of overhead.

I'd actually hope to keep the at the wall draw under 1000w since I bought a APC smart ups rated for 1000w to protect the system. It was a reasonable price (150 on ebay), but to get something higher than 1000w is ridiculously expensive.
 
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thilanliyan

Lifer
Jun 21, 2005
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Just a heads up...GTX480 SLI can draw as much as 624w FOR JUST THE CARDS.
http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_480_SLI/26.html

Add in a GTX280 which will say draw about 100w for running PhysX and you're left with about 250w for CPU, fans, HDDs, etc.. So you'll be cutting it close even with a 1000w PSU. PSUs are most efficient at 80-90% load I think so you wouldn't want to get right up near the maximum the PSU can output. I'd seriously consider another PSU.

OR you could underclock and undervolt the cards a bit since you probably won't be struggling for performance anyway and cut the power consumption.

EDIT: To clarify, for those who didn't read the link, that 624w is for Furmark.
 
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Keysplayr

Keysplayr

Elite Member
Jan 16, 2003
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thilanliyan said:
Just a heads up...GTX480 SLI can draw as much as 624w FOR JUST THE CARDS.
http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_480_SLI/26.html

Add in a GTX280 which will say draw about 100w for running PhysX and you're left with about 250w for CPU, fans, HDDs, etc.. So you'll be cutting it close even with a 1000w PSU. PSUs are most efficient at 80-90% load I think so you wouldn't want to get right up near the maximum the PSU can output. I'd seriously consider another PSU.

OR you could underclock and undervolt the cards a bit since you probably won't be struggling for performance anyway and cut the power consumption.
Click to expand...

"Peak: 472W 3DMark03 Nature at 1280x1024, 6xAA, 16xAF. Highest single reading during the test.
# Maximum: 624W Furmark Stability Test at 1280x1024, 0xAA. This results in a very high non-game power consumption that can typically be reached only with stress testing applications. Card left running stress test until power draw converged to a stable value."
 
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jbh545

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Jun 10, 2008
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I'd sell the 280 and just overclock the 480s instead of undervolting. That 624w isn't representative of what I do since I don't mess around with furmark. It's all 2560x1600 gaming with vsynch on, which usually keeps the cards well under 100% load.

Maybe I'll just try it and see what happens. Any idea how risky it is to just run a PSU too hard for a little while? I can get some idea of what it's drawing from the meter on my UPS.
 
Keysplayr

Keysplayr

Elite Member
Jan 16, 2003
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jbh545 said:
I'd sell the 280 and just overclock the 480s instead of undervolting. That 624w isn't representative of what I do since I don't mess around with furmark. It's all 2560x1600 gaming with vsynch on, which usually keeps the cards well under 100% load.

Maybe I'll just try it and see what happens. Any idea how risky it is to just run a PSU too hard for a little while? I can get some idea of what it's drawing from the meter on my UPS.
Click to expand...

Do the words BZZAPPP!!! and POOF!!! mean anything to you? ;)
 
S

SHAQ

Senior member
Aug 5, 2002
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It will shut down if it gets too high. Someone on EVGA forums tried 2 480's on a cheap 850 watt power supply with 4 rails and it shut down. A Corsair is much higher quality and has a single rail, 80 amps I think just on the 12V rail (960watts). It should be safe to run and see what the power consumption is like.
 
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jbh545

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Jun 10, 2008
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Keysplayr said:
Do the words BZZAPPP!!! and POOF!!! mean anything to you? ;)
Click to expand...

Yeah broseph but are you being facetious or am I doing something genuinely risky in this specific situation? I also have a single slot 9800gt I could toss in for physx but that might actually slow down the system from what I understand.
 
Keysplayr

Keysplayr

Elite Member
Jan 16, 2003
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jbh545 said:
Yeah broseph but are you being facetious or am I doing something genuinely risky in this specific situation? I also have a single slot 9800gt I could toss in for physx but that might actually slow down the system from what I understand.
Click to expand...

Actually, that 9800GT would be perfect for PhysX.
I wasn't totally being funny. You could risk popping the PSU if it doesn't have protection. And furthermore you could damage your PC's components. It "can" happen, not saying it will. Better to have more than enough power in the PSU dept. than almost enough. By far.
 
toyota

toyota

Lifer
Apr 15, 2001
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yeah just sell that gtx280 and buy something like a 9800gt or gt240 for physx. you will have money left over and theres no point in having a card that large that needs two connectors for physx.
 
Keysplayr

Keysplayr

Elite Member
Jan 16, 2003
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toyota said:
yeah just sell that gtx280 and buy something like a 9800gt or gt240 for physx. you will have money left over and theres no point in having a card that large that needs two connectors for physx.
Click to expand...

He already has a 9800GT to use. I agree he should sell the 280
 
J

jbh545

Member
Jun 10, 2008
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SolMiester said:
Would you need an extra card for physX with SLI GTX480's?
Click to expand...

http://www.maingearforums.com/entry.php?23-So-You-Want-To-Buy-A-GeForce

Well check out Batman here. At 2560 16xAA and high physx, dual 480's only average 42 whereas trip 480's average 77. I'd probably like to play at 2560 4xAA and keep the minimum above 60 at all times.

Not knowing how much that extreme 16xAA impacts the numbers, it's hard to say if I'll be able to do what I want without the extra physx card.
 
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thilanliyan

Lifer
Jun 21, 2005
12,040
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Keysplayr said:
"Peak: 472W 3DMark03 Nature at 1280x1024, 6xAA, 16xAF. Highest single reading during the test.
# Maximum: 624W Furmark Stability Test at 1280x1024, 0xAA. This results in a very high non-game power consumption that can typically be reached only with stress testing applications. Card left running stress test until power draw converged to a stable value."
Click to expand...

Yeah, that's why I said "can draw as much as". 3DMark03 at 1280x1024 is not really going to be pushing the GPUs very hard is it? Not sure why they used that for peak 3D power draw.

OCGuy said:
I thought 300w/card was the max with 1 6pin + 1 8pin? (Probably wrong here)
Click to expand...

I don't think that's an absolute maximum...more of a spec to be followed. I believe it is possible for the card to draw more than 300w.
 
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S

SHAQ

Senior member
Aug 5, 2002
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It will draw until the rail is overloaded or the PCI connector melts. lol
 
Daedalus685

Daedalus685

Golden Member
Nov 12, 2009
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jaggerwild said:
A GTX480 MUST HAVE 42 AMPS(on the 12 V rail), the Corsair HX1000 ONLY has 40 amps on a 12 volt rail BUT HAS TWO 40 amp 12 volt rails.
I would get a PSU with a higher ratting on the 12 volt rail like this one for example
http://www.performance-pcs.com/catal...ducts_id=22185
Click to expand...

LOL, that would put the gtx480 at over 500W of power draw.... I mean it's high.. but it isn't that high...

As mentioned, that is the recommendation for the whole system (across multiple rails, or on a single rail.. though no psu can supply full rated amperage to all rails at the same time).
 
Yuriman

Yuriman

Diamond Member
Jun 25, 2004
5,530
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jbh545 said:
That 624w isn't representative of what I do since I don't mess around with furmark. It's all 2560x1600 gaming with vsynch on, which usually keeps the cards well under 100% load.
Click to expand...


Vsync doesn't stop frames from being rendered, it just prevents them from being sent to the screen. If anything, the load is increased slightly.
 
exar333

exar333

Diamond Member
Feb 7, 2004
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toyota said:
yeah just sell that gtx280 and buy something like a 9800gt or gt240 for physx. you will have money left over and theres no point in having a card that large that needs two connectors for physx.
Click to expand...

+1. 280 is a little overkill for just Physx; a 9800gt or 9600gt (not cot-down version) would be ideal and would work just as well with minimal power usage.
 
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