6950 Crossfire

[Fearthis909]

I'm looking to crossfire two 1gb 6950's with the power supply noted above.

My system specs are as follows:

Amd 955 Black edition from 3.2 overclocked to 3.61ghz

8gb XMS3 1600MHZ corsair ram

Seagate Barricuda 500g 7200 RPM

And of course the 2 6950's (Will not being overclocking)

I was curious on peoples opinions if I could power all of this with my power supply.

Thank for reading my post .

 

[WT]

Ehh, I see no PSU noted above

 

[Fearthis909]

Sorry it's a corsair tx650W PSU

 

[WT]

Fear, good news for you is your TX650 looks like it should be fine with a pair of 6950's.

http://extreme.outervision.com/psucalculatorlite.jsp

Just plug in your system values and this will give you a good indication of whether it will work reliably or not.

 

[Termie]

Sorry it's a corsair tx650W PSU

You have 52a on the 12v rail. That's 624w. An HD6950 crossfire system pulls 470w on an i7-920@3.3: http://www.anandtech.com/show/4239/nvidias-geforce-gtx-590-duking-it-out-for-the-single-card-king/16. Your system would probably pull a bit more, but you still have enough headroom to give it a go. I'd take it easy on the overclocks on those cards, though, and probably avoid pushing the Powertune current control up much.

I just played around with that PSU calculator and it came up with 490w for your system (actually 514w if I include a DVD-Rom drive, which is silly since it's usually not running). Almost exactly what I would have estimated based on Anandtech's results.

 

[Fearthis909]

Thank you so much guys I won't be overclocking these cards but will my processor from 3.2 to 3.61ghz make a lot of difference to my power pull? So I should be all good

 

[Fearthis909]

http://www.corsair.com/tx650w.html

As it is 80 percent energy efficient does that mean it's only pushing out 520 of the 650w?

 

[Plimogz]

As it is 80 percent energy efficient does that mean it's only pushing out 520 of the 650w?

yeah. But putting it this way would be less ambiguous:

As it is 80 percent energy efficient does that mean it's only pushing out 650 of the 812.5w?

and even that is a questionable statement...

The important figure the the number of amps available on the +12V line to power your graphics cards. With regards to that, Termie already...

 

[Elfear]

I honestly wouldn't chance it on a 650W PSU. I know I've said this before in the PSU section but I pulled 770W from the wallplate running through the STALKER: COP benchmark. That's equal to about 640W since the PSU I was using was ~83% efficient. My cards were overclocked but nothing over the top. I wouldn't want to run my PSU that close to the limit. Go for at least a high-quality 750-800W PSU.

That being said, I've loved my 6950's. Power through everything I've thrown at them at 2560x1600.

 

[3DVagabond]

I honestly wouldn't chance it on a 650W PSU. I know I've said this before in the PSU section but I pulled 770W from the wallplate running through the STALKER: COP benchmark. That's equal to about 640W since the PSU I was using was ~83% efficient. My cards were overclocked but nothing over the top. I wouldn't want to run my PSU that close to the limit. Go for at least a high-quality 750-800W PSU.

That being said, I've loved my 6950's. Power through everything I've thrown at them at 2560x1600.

I too would recommend caution. For gaming and regular use at stock clocks (both CPU and GPU) I'd say you're fine. I wouldn't be O/C'ing and running benchmarks that take the system to 100% though. Typically, I'd say 750W is what you should have, with 850W if you were a conservative builder.

 

[OVerLoRDI]

You will be CPU limited with crossfire 6950s on a Phenom II X4 at that speed. I had a Phenom X4 940 running at 3.5Ghz with 2 6970s. The second I swapped in a Sandy Bridge, I go almost a 50% performance increase in Metro 2033 without overclocking the CPU. Phenoms are just not enough for high end dual GPU rigs (most of the time)

 

[dpk33]

If you are planning on keeping the Phenom II setup and want to get the most out of it, you will need to push your cpu further. It can go way further than 3.61. I got mine up to 4.0 with a $25 Hyper 212+. Even then, it will bottleneck crossfired 6950s.