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Will a 650W PSU be enough to run crossfire 6950's?

G

gregr507

Junior Member
I just recently built my parents a new computer. It has a 2500k, hdd, ssd, 16 gb of memory, and currently 1 6950 (1 gb model). I used to have crossfire 6950's, but put one of them in their new build. I just pulled the trigger on a 7970 a few minutes ago, so I was thinking of giving them my other 6950 so they could crossfire them.

My dad loves civ5 and was blown away at the level of detail when I cranked the settings up with their new build. I want to give them my 6950, but the problem is I wasn't planning on setting up a crossfire rig for them, so the computer only has a 650W PSU. It is this exact model (Corsair TX650):

http://www.newegg.com/Product/Produc...82E16817139020

I know a 650 W psu would be cutting it pretty close for this system. What do you guys think, would it be enough? Or would a new PSU be required as well? Thanks a lot!
 
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Great! I'm glad to hear it should work. If not I can always upgrade their PSU later.

One more question since I already have the thread open, how will I know if the 650W isn't enough? Will the computer crash, artifact, or what?
 
Short answer is yes.

128W peak power draw while gaming for each = 256W total. http://www.techpowerup.com/reviews/HIS/Radeon_HD_6950/27.html

Even if we pretend like all the rest of the system is maxing out their TDP as well for some reason, that's only another 200W at most.

Total is about 450W, far less than the sustained 650W the PSU can pump out (nice choice btw, I used to have that exact PSU in my primary system).

Even if you overclocked heavily AND overvolted, you would probably still have a 50+ watt cushion. And that's for worst-case scenarios (not counting Furmark which presumably your folks do not run).
 
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blastingcap said:
Short answer is yes.

128W peak power draw while gaming for each = 256W total. http://www.techpowerup.com/reviews/HIS/Radeon_HD_6950/27.html

Even if we pretend like all the rest of the system is maxing out their TDP as well for some reason, that's only another 200W at most.

Total is about 450W, far less than the sustained 650W the PSU can pump out (nice choice btw, I used to have that exact PSU in my primary system).

Even if you overclocked heavily you would probably still have a 50+ watt cushion. And that's for worst-case scenarios (not counting Furmark which presumably your folks do not run).
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Very reassuring, thank you. I just ordered a kill-a-watt so I can check the actual power draw since I had 30$ in amazon giftcards burning a hole in my pocket anyway lol.
 
gregr507 said:
Very reassuring, thank you. I just ordered a kill-a-watt so I can check the actual power draw since I had 30$ in amazon giftcards burning a hole in my pocket anyway lol.
Click to expand...

Then you need to multiply by the efficiency of the PSU. That Corsair unit is around 80% efficient at ~450 loads IIRC. So if you are pulling 500W at the wall (PC only, no monitor or speakers or printers or anything else), the PSU is really only being stressed 0.8 * 500 = 400 watts.
 
blastingcap said:
Then you need to multiply by the efficiency of the PSU. That Corsair unit is around 80% efficient at ~450 loads IIRC. So if you are pulling 500W at the wall (PC only, no monitor or speakers or printers or anything else), the PSU is really only being stressed 0.8 * 500 = 400 watts.
Click to expand...

I will keep that in mind, thanks again man you've been very helpful
 
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