Could a 650 watt power supply run two HD 7970's?

[Isaacwidnall]

Hi, I am just wondering if a corsair hx 650 gold psu could run two gigabyte HD 7970's in crossfire? Thanks.

 

[ThatVietGuy]

No.

 

[10esseetony]

For a little while, sure, depending on your other components of course. But it's sure to let the smoke out that the engineers so diligently worked to put into it after extended periods of maximum draw, especially as it could easily peak beyond 650watts.

I have a 14 core/28 thread Xeon, the whole system uses about 150watts under load, and then I have a AMD FX something or another (8350?) that uses a whopping 240 watts under load, for a measly 4 cores/8 threads. I've measured my Radeon R9-280X's (basically same GPU as yours) as using an additional 225watts under load, but it's highly variable, up and down. (The measurements are from the wall, not the power supply.)

Long story short, I wouldn't recommend it long term. A week or two, eh, sure, the PSU should shutdown rather than let the smoke out, until you get something closer to 850watts.

 

[djreedj]

I would get a 850w Supernova by EVGA Gold rated. Its a great psu and will give you a bit of headroom. Never skimp on a PSU.

 

[toyftw]

Hi, I am just wondering if a corsair hx 650 gold psu could run two gigabyte HD 7970's in crossfire? Thanks.

Hi - In terms of having enough +12v amperage to run the system, there is enough. However, you have
two issues to consider, you'd be running the PSU at a very high % to it's total avail power and would significantly
shorten it's life (and an occasional spike could shut the PSU down), secondly that PSU has only
two pcie connectors, while two 7970's require 4. Yes, you could use molex to pcie adapters, but I'd strongly advise against.

If you really want to CF two 7970's, upgrade your PSU.

 

[10esseetony]

I'd never tested my primary system before, an i7 5820K, with twin 280X's. With the CPU at 100% and running FurMark in CF, the cards were only running at 74%, but I was pulling up to 690watts from the wall. 690watts multiplied by an efficiency of, let's be conservative and say 92% (best case) means the PSU was putting out 634.8 watts.

Technically my PSU is only up to 88% efficient, which means it was only putting out 607.2watts.

So, yes, it's possible, but I wouldn't.