How large PSU for 7970 CrossFire?

RaistlinZ

Diamond Member
Oct 15, 2001
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I currently have a Corsair HX750 PSU. I'm sure 7970 CrossFire would be pushing it with this, but how large of a PSU would I need?
 

RavenSEAL

Diamond Member
Jan 4, 2010
8,670
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You should be fine but I guess if you REALLY wanna be safe, around 900w should be the mark.
 

Satire

Junior Member
Dec 30, 2011
1
0
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7970 requires less power than a 570, so CF 7970 on corsair HX 750w will work fine
 

lehtv

Elite Member
Dec 8, 2010
11,900
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Will work fine on a 750W corsair. 200W per card + 200W for the rest of the system (OC'd i7) ~ 600W/750W ~ 80% at full system load which is fine. Corsairs are designed to handle that sort of load without issues.
 

BoomerD

No Lifer
Feb 26, 2006
62,678
11,017
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http://www.guru3d.com/article/amd-radeon-hd-7970-review/8

Our test system is based on a power hungry Core i7 965 / X58 system. This setup is overclocked to 3.75 GHz. Next to that we have energy saving functions disabled for this motherboard and processor (to ensure consistent benchmark results). On average we are using roughly 50 to 100 Watts more than a standard PC due to higher CPU clock settings, water-cooling, additional cold cathode lights etc.

We'll be calculating the GPU power consumption here, not the total PC power consumption.

Measured power consumption

System in IDLE = 163W
System Wattage with GPU in FULL Stress = 355W
Difference (GPU load) = 192W
Add average IDLE wattage ~3W
Subjective obtained GPU power consumption = ~ 195 Watts
Mind you that the system wattage is measured at the wall socket.
 

Elfear

Diamond Member
May 30, 2004
7,096
640
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As long as you're not overclocking the cards much you should be fine. I was getting random shut-downs with the parts in my sig (cards were overclocked) on a quality 800W PSU. That happened playing Starcraft II and sometimes running through the STALKER: COP benchmark. My Kill-O-Watt indicated 770W at the wallplate. A new 1000W PSU solved the issue.
 

DooKey

Golden Member
Nov 9, 2005
1,811
458
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If you are going to OC and OV the cards and run them 100% folding or something like that and run your CPU 100% folding as well then I'd go at least 850w. If you are just gaming then your 750 will be just fine.