I don't place much faith in APEX as a PSU provider. If you are planning to get a new PSU, try something like this:
SeaSonic S12II 520 Bronze 520W ATX12V V2.3 / EPS 12V V2.91 80 PLUS BRONZE Certified Active PFC Power Supply $59.99http://www.newegg.com/Product/Product.aspx?Item=N82E16817151094
For my system, I'm not completely sure if it's the PSU, the mobo, or even the hard drive itself. I would usually start to narrow down the problem by replacing the PSU first. In case the PSU is not the problem, you will still have a reliable PSU for future builds.