2 hd 6950s, 600w psu?

SpringWater

SpringWater

Member
My friend is planning to crossfire his 6950s and all he has is a 600w corsair cx 600 psu, is that enough? if not what do you recommend?
 
No it will not. you have 46A on the 12V rail and of those, ~35A will be just for just the graphics cards, leaving 11 for the rest of the system, which isn't enough.

I would go 700+W Corsair, SeaSonic, Silverstone, XFX, PCP&C or Enermax unit
 
Aastii said:
No it will not. you have 46A on the 12V rail and of those, ~35A will be just for just the graphics cards, leaving 11 for the rest of the system, which isn't enough.

I would go 700+W Corsair, SeaSonic, Silverstone, XFX, PCP&C or Enermax unit
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The max used by the whole system on anandtech was like 320, so with 2 it would be 450-500w, and 12*46=532w, not a ton of headroom but he shouldn't be maxing them all the time with that much power.
 
not all the wattage is on the 12V rail, so i would not recommend it...though i did do 2 9800GTX+ on a 550W rosewill...still would not recommend that.
 
I wouldn't recommend doing it either. 700-750 watts from a good company would be fine.
 
Couple of things:

1. http://www.bit-tech.net/hardware/2010/12/16/ati-radeon-hd-6950-review/10

Which would be 43A just for the cards. The power draw varies from source to source, but generally you are looking at 400-500W for the graphics cards alone. Paired with a stock 95W CPU, that is 495-595W, without any overclocks, taking into account any fans, motherboard, memory hard drives or external devices. 600W isn't enough, especially with an average PSU like the CX600 is

2. You only need to overload the PSU once for it to die, so saying "so long as it isn't always at max load" is almost as stupid as recommending a PSU being on the edge. It will either be good enough or it won't, never will it sometimes be ok as you are saying

3. For the sake of efficiency, you don't want it near full load. They are most efficient around 60-70%, so buying a PSU that has more watts and is more expensive will, in the long run, save money
 
Most test show how much the average system pulls as a whole. A 6950 at idle pulls around 30W. When its not powered down about 130W. When its under load about 160W. A its max load it can pull about 200W. Theoretically in C/F they could pull up 400W. With that a 600 quality power supply could do them in C/F. But it would be close to its max with the rest of your system added to it when under load. A 750W quality one would be better and would not be running at its max every time your system was under load.
 
jonnyp11 said:
Or keep the corsair and sell the 6950 then get a 7950

And i thought the psu would just put out what it could and the graphics cards would just throttle down.
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The thing is that he has one 6950 already and he can get another one for like $150 cause there is a sale in his local store. This way he won't spend a whole bunch of money and he will get a crap-ton of performance. (he has 2gb models)
 
jonnyp11 said:
Or keep the corsair and sell the 6950 then get a 7950

And i thought the psu would just put out what it could and the graphics cards would just throttle down.
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No, if the power supply cant give the graphics card enough juice, you will get instability, artifacts, lower performance or a blown psu, or a combination of any of these. The graphics card wont just sip power, if that were the case you could theoretically power a 690 on a 300w unit, it will just throttle down really hard, which you know isn't true
 
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