Psu for 6870X2 crossfire

[cainy1991]

okay guy I have only just finished updating my PC a few weeks ago..
and then I go and get another present...that just so happened to be...
a new video card!

a powercolor 6870x2 (duel gpu 6870)

and damn! this thing is beast...and for $390
I think its time for my gtx 460 and 6870 to be sold
and other one of these to be purchased.

I feel like such a noob asking a psu question
within weeks of asking my last...

-question-
to run two of these beasts(overclocked) along with my
current hardware what wattage psu would I need
to be looking at..??

-current rig-
phenom 960t-cpu HEAVILY OC'ED
msi 870a fuzion-mobo
scsi raid card
-drives-
1tb sata II drive.
4x scsi 10k


I was hoping I would get away with using an 850... but when I think about it I dont like my chances..

 

[WR2]

Hello cainy1991;

TechPowerUp measured the peak draw of a stock PowerColor HD 6870 X2 @ 245watts
I think a premium 850W PSU could handle the max load OK. And I think the more typical gaming load would be well within the capability of a 850W PSU.

 

[WR2]

On the other hand the maximum power draw (Furmark) was a hefty 353W and might be closer to the draw if you do something like a max OC on the GPUs.
700W for the GPUs alone? That premium 850W PSU is sounding a bit light for a 'worst case' scenario.

 

[esrever]

I would advice not going with 6870x2 crossfires as quad crossfire is not very good.
the performance gain isn't the best when scaled pass 2 cards and you'd only see a real performance increases in artificial benchmarks.

 

[festerovic]

is it possible to use a single 6870 card to go tri-crossifre in this scenario?

 

[cainy1991]

thanks for the feedback WR2.
So I'm going by the understanding I should
now start looking for a 950-1000 watt
I'm roughly calculating the OC on my cpu to draw around
130-150 @ 4.5 all cores unlocked (thinking of it as a X6 overclocked)
in addition to your calculation of 706W for the GPUs
bringing me over 850 already.. so if yeah definitely higher than 850.
Thanks!

 

[cainy1991]

Best answer selected by cainy1991.

 

[esrever]

is it possible to use a single 6870 card to go tri-crossifre in this scenario?

Im pretty sure it works because you can put a 6970 with a 6990 for tri crossfire.