Here are the official ATI power supply requirements for the ATI Radeon HD 5770 and 5750 video cards:
450 Watt or greater power supply with one 75 watt, 6-pin PCI Express® power connector recommended
600 Watt or greater power supply with two 75 watt, 6-pin PCI Express® power connectors for ATI CrossFireX™ technology in dual mode
The recommendations are for an entire pc system.
Corsair and Seasonic are two brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty (in the USA).
Great stuff... I took your advice.. and i'm sure i'll be saving some money... (There's a good deal on an Antec TP-650)
Well done for both, listening on a proper advice and choosing a good PSU.. Although a good 550W PSU will be adequate to your needs, the 650W PSU (as chosen by you) will give that extra headroom for any future expansion plans such as adding extra hard drives and/or optical drives, going overboard with your CPU overclocking etc.
Thanx for all the input... Actually my system does have several hard drives - 1 for data, 2 in Raid 0 for a 'scratch drive' and 1 SSD for the OS. It's all in an Antec 900 Two.. so it's got lots of fans to power up too... and lots of bus-powered USB devices.. all on a Asus p7p55d-e pro overclocked to a 190 Bclk