Originally Posted by Dark
For those of you that are claiming a 750w psu is enough, have you measured the draw from the wall socket?
From all that I had read before picking up my second 570, all 'magazine/site' notes show total system power approaching 600w+ and some folks on here reporting even more.
If this is the case I'd be reluctant to strain my PSU with loads near 700w (factor in overclocks and/or additional drives) so I'll more than likely pick up the 1000w corsair just to play it safe.
My conclusion, will a 750w PSU work? Yes.
Will it work well? If it's a good unit then yes.
Would you be better off with an 850-950 unit? Absolutely.
The rating of the PSU is not its capacity in regards to what it can draw from the wall. Instead, it's the capacity that it can provide to the system.
So let's say that we have a system that is causing the power supply to pull 650W from the wall during a load test. Now let's also say that the efficiency is exactly 85% at the time of this power draw. This means that the computer system is pulling 552.5W from the power supply (650W * .85). So for this system, a quality 650W would be fine.
But now I'm curious: you have a TX750 powering your system and you have two GTX 570s in it. So, what's the highest power draw you've ever seen? Also, why are you saying things like "My conclusion, will a 750w PSU work? Yes. Will it work well? If it's a good unit then yes. Would you be better off with an 850-950 unit? Absolutely."
? I mean again, you have a 750W power supply powering your system that has two GTX 570s in it. So if you are saying these things, then why don't you have a 'bigger' power supply?
Finally, don't worry about straining your PSU. According to these two excellent articles by Phaedrus2129, a quality 750W is right in the sweet spot for powering a modern system with two 570s in it: