Can you use a 650w psu or do you need a 750w psu?

my computer components are:

Asus P6X58D Premium

Intel Core i7 930 Processor

Noctua NH-U9B-SE2 Performance CPU Cooler

G.Skill 6GB KIT DDR3 1333Mhz

XFX ATI HD 5750 1GB DDR5, PCI-E, 700/4600Mhz

Creative Sound Blaster X-Fi Titanium

Samsung BluRay Combo SATA DRIVE

2 500gb Wd Caviar Green

thank you.