i already have 1 5770 and looking to buy another but the box says it needs 650w of power to run them in crossfire, but the thing is i have found a psu that i would like to get which is a Coolermaster RealPower 620W Modular PSU will this power them along with the rest of my system. i found a website that calculates the power that your system needs eXtreme Power Supply Calculator and it says that 550w is enough with a 35% capacitor aging.
System Specifications:
AMD Phenom II 955 Black Edition
Asus M4A785TD-V EVO
HIS Radeon HD 5770
Akasa AK-968 CPU Cooler
Seagate 500GB Harddrive
LG Supermulti DVD drive
Antec 120mm TriCool Green L.E.D. fans x2
Antec 120mm TwoCool fan
Antec 140mm TwoCool fan
System Specifications:
AMD Phenom II 955 Black Edition
Asus M4A785TD-V EVO
HIS Radeon HD 5770
Akasa AK-968 CPU Cooler
Seagate 500GB Harddrive
LG Supermulti DVD drive
Antec 120mm TriCool Green L.E.D. fans x2
Antec 120mm TwoCool fan
Antec 140mm TwoCool fan