Do I need a better PSU for crossfire?

[carbonfountain]

Hi everyone.

Recently I purchased a new computer. The relevant parts are as follows:

PSU: Corsair Enthusiast PSU TX650v2 (650W)
CPU: I5-2500k
GPU: XFX Double D 7950
Motherboard: Biostar TZ68A+

Due to a problem with Amazon shipping I didn't get the PSU yet, and now I'm wondering if I should buy a higher capacity PSU for doing Crossfire later on. I understand that my motherboard should support crossfire, but I don't know if a 650W PSU will pump enough juice for 2x HD 7950s later on, particularly if I also plan on overclocking the CPU and the GPUs.

Any input would be appreciated!

 

[xtreme5]

yes, you need 750w.

 

[dudewitbow]

i would recommend at least 700 if you want the saftey wall of being able to overclock both gpu and cpu with alot of attachments on.

 

[cin19]

Yes, check the link : http://www.guru3d.com/article/radeon-hd-7950-crossfire-review-2-and-3way/5

 

[sincreator]

I'd probally go to an 850w corsair/seasonic/antec PSU myself. At least there would be a bit of breathing room for future overclocking, once you get the second card. The article that cin19 linked mentions at least a 700w PSU for stock clocks on everything, but says to go bigger if you want to overclock. The price differance is usually only about $20, so why take the chance IMO.

 

[carbonfountain]

Thanks everyone, I will look for a unit with at least 750W on the 12v rail instead. The only reason I asked was because when I played around on the extreme vision PSU calculator, it gave me a recommended 613 watts for 2x 7950s. The result seemed very surprising to me, but after hearing your responses I think I will take it a few steps up for safety margin.

 

[cuecuemore]

You're just fine with two of them on the Corsair 650w if you run everything at stock, you wouldn't even be pulling 600w from the wall. For heavy overclocking or if you want to run at a lower percentage of PSU max output then a quality 750w unit would be the way to go.

 

[coper210]

on the newegg power supply calculator it says 750W but I would go ahead and go with an 850W just incase

 

[carbonfountain]

It may seem a tad pricey, but the Corsair HX850 is what I'd recommend @~$155:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139011&Tpk=hx850

The Corsair HX750 is $20 cheaper and is known to be able to output well above 750W of power perfectly fine, but I always think it's worth spending extra on an overkill PSU. All your components depend on it, so why just get the minimum?

I know Corsair has multiple lines like Builder, Enthusiast, Professional and Gaming.

Are there any intrinsic differences between these PSUs (other than efficiency) that make the HX series so much more expensive?

 

[dudewitbow]

I know Corsair has multiple lines like Builder, Enthusiast, Professional and Gaming.

Are there any intrinsic differences between these PSUs (other than efficiency) that make the HX series so much more expensive?

its more or less quality of parts what you pay for. quality of parts also effects heat effeminacy, so higher efficiency generates less heat, which in return ages the psu slower.

 

[carbonfountain]

its more or less quality of parts what you pay for. quality of parts also effects heat effeminacy, so higher efficiency generates less heat, which in return ages the psu slower.

Got it. I haven't been able to build it yet as I'm still waiting on the PSU. I plan on getting a 750W given all of the discussion here, but in all honesty I can't see myself buying a $150 PSU when I got the remaining components for only $700 or so...

 

[carbonfountain]

Best answer selected by carbonfountain.

 

[Mousemonkey]

This topic has been closed by Mousemonkey