I just acquired a second radeon 4870 card for a crossfire setup. My psu is a Corsair Hx620 which should be plenty in most cases. But the things is i have a heavily overclocked core i7, x58 board, 3 hard drives, 8 120mm fans, a big 250mm SoB fan, cold cathodes, a sound card and a somewhat powerful pump for my cooling system. I always thought big power supplies where a bit overkill, but now i am wondering.... Will my 620 watt cut it? It look very borderline... Used a psu calculator and it sugested a 660 watt. What do you guys think of all this?