6950 Crossfire Question

R

Rauelius

2[H]4U
Joined
Jan 2, 2008
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Thinking about getting a 6970 xfire for my brand new sandy bridge build and moving the 5850 xfire to my Thuban. Will the PSU in the SB build be beefy enough to handle them?
 
BTW, its to get the Thuban to perform better, and figured I'd have a better time upgrading the SB and moving them to the Thuban. Also considering a single GTX580.
 
If you run the 6950s at stock, then yes, a 750TX is enough. If you intend to unlock, overclock, and possibly overvolt them, be aware that the power usage can increase by 50 watts or more (per card), pushing them over 6970 power usage. In this case, a 750TX will still technically be "enough", but depending on your other system components you may be pushing the PSU pretty hard.

PSUs get hot, noisy and less efficient when you go past 80% of their rated load:

http://hardocp.com/article/2007/10/16/corsair_tx750w_power_supply/4
 
Your PSU is plenty for your GPUs. I'm running OC'd and unlocked 6950s with powertune +20% on a 750 watt and my CPU uses a lot more power than Sandy Bridge. The most I drew from the wall was about 600W.
 
Thanks for the info guys...not looking to do eyefinity, so would the 2GB one be overkill, also, anyone hear of the 1GB 6950's unlocking to 6970's?
 
I run an i5 750 clocked by more than 50% and overvolted a fair bit. This is more power than an i7 2600K with a very basic overclock will use. I also run two HD6970s, which use more power than HD6950s.
Out of the PSU, I use:

140W idle
190W mid-clocks (GPU-accelerated flash/video etc.)
270W lightweight gaming (GZDoom etc.)
380W midweight gaming (Magicka, Heroes of Newerth)
460W heavyweight gaming (Left 4 Dead, Bad Company 2)
490W Crysis (in certain places), Furmark
620W Absolute max (OCCT PSU stress test)

On that basis, your system will probably never break the 600W barrier, probably not even the 550W barrier. A 750W PSU is more than sufficient for your purposes.
The 1GB 6950s do not unlock. Neither do any 6950s that are not based on the AMD reference design.
 
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