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can i run dual 7970's or 7950's

post #1 of 82
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pelase take a look at my current psu http://www.amazon.com/gp/product/B008RJZQSW/ref=oh_details_o06_s00_i01?ie=UTF8&psc=1

I am looking at running dual http://www.amazon.com/Sapphire-DL-DVI-I-SL-DVI-D-PCI-Express-11197-12-40G/dp/B008PQAE98/ref=sr_1_1?s=electronics&ie=UTF8&qid=1362544386&sr=1-1&keywords=7970+1ghz

how much of a difference is the crossfired 7950's vs 7970's? Do i need to upgrade the psu?

Also if you can please tell me which is the best 7950/7970 there is, currently im using a XFX

I would also be willing to go with Nvidia, since the screen flicker is an issue. I just dont know if PSU can handle the power needed
Edited by Baby Jai - 3/5/13 at 8:49pm
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post #2 of 82

This PSU has way more than enough power.

 

I don't know how different the 7950s are from the 7970s.

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post #3 of 82
your psu should handle 2 HD 7950 or HD 7970 cards. what card are you currently running ? is it a XFX HD 7970 ? your sig rig says 1250 mhz clocks. is that on stock cooler ?
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post #4 of 82
as a reference...

I had a similar thread running a bit ago when I went crossfire 7970s...my tower with 2x sapphire 7970s and my i5-3570k (all overclocked) draws 655W from the outlet (highest seen using a kill-a-watt during 3dmark13 and unigine valley benchmarking)

though YMMV depending on your drives/peripherals


also...get it off newegg...$439.99 after $20 MIR

http://www.newegg.com/Product/Product.aspx?Item=N82E16814202001
Edited by flash2021 - 3/5/13 at 9:16pm
post #5 of 82
Quote:
Originally Posted by flash2021 View Post

as a reference...

I had a similar thread running a bit ago when I went crossfire 7970s...my tower with 2x sapphire 7970s and my i5-3570k (all overclocked) draws 655W from the outlet (highest seen using a kill-a-watt during 3dmark13 and unigine valley benchmarking)

though YMMV depending on your drives/peripherals

 

To take this a little further:  if the PSU is 85% efficient while pulling 655W from the wall outlet, then that means the system is pulling almost 557W from the PSU (556.75W).

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post #6 of 82
Quote:
Originally Posted by TwoCables View Post

To take this a little further:  if the PSU is 85% efficient while pulling 655W from the wall outlet, then that means the system is pulling almost 557W from the PSU (556.75W).

ah yes, good info! and ideally I should be at about 91-92% efficiency per corsair's efficiency vs load graph, since my ax860i is platinum, then that's about 603W-ish...def a good point to understand when discussing PSU functionality thumb.gif

(and thanks for the reminder to update my rig sig)
post #7 of 82
Your PSU will be able to run either combination.
Quote:
Originally Posted by TwoCables View Post

I don't know how different the 7950s are from the 7970s.

Power wise, the 7970 is like ~50w more consumption at stock speeds due to the extra shaders/clocks. But still, a good 750w should be able to handle that much.
Quote:
Originally Posted by flash2021 View Post

ah yes, good info! and ideally I should be at about 91-92% efficiency per corsair's efficiency vs load graph, since my ax860i is platinum, then that's about 603W-ish...def a good point to understand when discussing PSU functionality thumb.gif

For platinum PSU's, the efficiency is sorted like this:

20% load: 90% Eff.
50% load: 92% Eff.
100% load: 89% Eff.

But yeah, unless you truly know you're using the 100% of the PSU's capacity, it is safe to assume 90-92% efficiency.
Edited by Starbomba - 3/5/13 at 9:26pm
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post #8 of 82
Quote:
Originally Posted by Starbomba View Post

Your PSU will be able to run either combination.
Power wise, the 7970 is like ~50w more consumption at stock speeds due to the extra shaders/clocks. But still, a good 750w should be able to handle that much.

 

I'm talking about the difference in performance.

It's a computer!
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Hard DriveHard DriveHard DriveOptical Drive
250 GB Samsung 840 EVO (C:\) 250 GB Samsung 840 EVO (D:\) 150 GB WD VelociRaptor Samsung SH-S243N 24x DVD Burner 
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post #9 of 82
Quote:
Originally Posted by TwoCables View Post

I'm talking about the difference in performance.

It's significative in most things.

Still, if you OC the 7950 (800/5000 MHz) to the same clocks as the 7970 (912/5500 MHz), you end up with very similar results.

Then again you could OC the 7970... but i'd say bang for buck the 7950 is better, especially if you can get your hands on a 7950 w/ 7970 PCB (more and better power phases, better circuitry)
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post #10 of 82
at the same clocks HD 7970 is 3 - 7% faster than HD 7950 depending on game. a HD 7950(1000 Mhz) would match or exceed a HD 7970(925 Mhz) and a HD 7950(1125 mhz) would match / exceed HD 7970 Ghz(1050 mhz).

http://www.techpowerup.com/reviews/HIS/HD_7950_X2_Boost/31.html
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