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7970 Crossfire - is my PSU strong enough?

Addicted

Addicted

Addicted

Soldato
Joined
23 Jul 2007
Posts
2,823
Location
Worcester
Hey Guys,

I'm rolling with this spec currently:

i7 950 @ 4.2ghz, 6gb ram.
4 hdds, 1 ssd.
7970 Lightning (watercooled)
Llaing D5 pump for CPU/GPU

8 case fans (6 on the 360 rad).

Can I fit another 7970 in for crossfire?

PSU is a Corsair HX 750W ATX Modular SLI Compliant Power Supply - supposedly good for 850W when I read the reviews.
 
Addicted said:
So I'd be fine running it even though it's the minimum? I'm pretty sure on the review for that PSU they said it would actually be ok up to 850W!
Click to expand...

750W will be fine for stock, if you intend to overclock the cards you probably want a stronger psu though.
 
850W would give you breathing room if you plan to overclock both cards.

A small overclock on the lightning wont change power consumption by any significant amount.
 
Well my 680 SLI set up drew only 450W from the wall while overclocked and gaming.

Bearing in mind 7970 is slightly more power consuming, I think you're more than fine unless you run SB-E.
 
What's SB-E ?

And one final question - can I run my Lightning overclock along side another 7970 ok? Will it be affected or need to be lowered etc?
 
That PSU is more than enough for a pair of 7970's. My system draws around 450w from the wall under load with a 4.8ghz I5 and crossfire 7950's at 1200/1600 and lots of other stuff.

Tonester0011 that is very high especially for 7970's what did you use to measure ?
 
MOOGLEYS said:
That PSU is more than enough for a pair of 7970's. My system draws around 450w from the wall under load with a 4.8ghz I5 and crossfire 7950's at 1200/1600 and lots of other stuff.

Tonester0011 that is very high especially for 7970's what did you use to measure ?
Click to expand...

Yup I ran two 480s with a similar watercooling setup on a ax750 so 7970 should be fine as they do not draw anywhere near as much.
 
an i7 950 is still a pretty power hungry chip (130w like SB-E iirc).

A good 750w will cut it IMO (which you have), you may only start to see it struggle if you have both 7970's running over 1.3v, which benching aside, no-one is insane enough to use.
 
MOOGLEYS said:
I would say it's not very accurate. Have you got lots of other stuff plugged in as well possibly into an extension ?
Click to expand...

An extension is connected to it, on the extension is my phone charger and my PSU.

My 1200i reads nearly identical to my power meter <5w.
I think its a lot more accurate than you first thought, no different from Gregsters computer peaking at 1150w.
 
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