Originally Posted by Nickum32
Well when I read the professionals saying that a two 7970 setup is only pulling 700w from the wall, i have a hard time believing that 1000w won't be enough.
Yeah, but if the PSU is 90% efficient while pulling 700W from the wall outlet, then the computer is pulling 630W from the PSU. If it's 85% efficient, then the computer is pulling 595W from the PSU.
So, the power that the PSU is pulling from the wall outlet is not being subtracted from its capacity; only the amount of power that's being pulled by the computer is. Another 7970 would only add another ~200W under full load. So here again we're arriving at the same power draw I calculated above from Guru3D's review. Even adding 250W still runs under 900W (at 880W).