another psu requirement question

Considering adding a second 4870 to my system (the egg has them for $195). I have a 650W thermaltake toughpower.......will it be enough. I'm already running 1 4870, plus a q6600@3.6ghz. Not to mention a few hard drives, and an assload of fans. Theoretically, I think with a second card, at max consumption, I could potentially draw 650W. I know that's not likely, and the psu is rated for 80% eff. Anyway, is it enough?

The combined 5v and 3.3v max is: 180W (hard to see, almost looked like 160w)

Which would leave 470w for 12v side (if its 180w for 5v/3.3v).

Using the PS Calculator, just the CPU and 4870/CF with the CPU @ 60% TDP 384W, which leaves 86w.

Hard to say how much a game (different games may be more CPU intensive) would put on a CPU (which could be less then 60%), but normally the quad isn't going to get fully utilized which would change that figure drastically if all 4 cores were under load.

eXtreme Power Supply Calculator Lite v2.5

Just put in your stuff to see what a general wattage for CPU 85% and system load at 90%.

Too bad you can't select your PSU for it to tell ya if your making it difficult.