Hi there,
as autotech says the PSU is a very important and often overlooked part of any new build so it is worthwhile getting a good solid model.
On my own GA-990FXA-UD5 I have a Corsair 620Watt Modular unit which has happily powered this board along with a 1090T CPU (O/C'd), Noctua NH-D14 CPU Cooler with two fans, 16 Gig of RAM, two ATI 6770's in CrossFire, two ADATA 60GB SSD's, four HDD's, a DVD/CD burner, six 120mm System fans and various USB peripherals without an issue.
So my recommendation would be something like the Corsair 650Watt Enthusiast or Pro Series modular unit.