I currently got a single 5850 card powered by a 550W 80plus certified PSU. I'm planning on getting another 5850 and was wondering if this PSU is enough to power another card.
I've got a q6600, 4gb ram, dvdrw, and 1 500gb HD hooked up onto this PSU as well
Roughly.
375w with what you have atm, no overclocking, no mining.
625w with what you have atm + adding another 5850 without overclocking & without mining.
675w with what you have atm + adding another 5850 with just overclocking.
937.5w with what you have atm + adding another 5850 without overclocking. Mining 24/7.
1012.5w with what you have atm + adding another 5850 with overclocking & 24/7 mining.
Phaedrus Quick'n'Dirty PSU calculator is what I go by for quick n dirty.