Final Compability Check For Mid Range Gaming PC Build

A Seasonic MK12II 520W is enough.

Everything Looks good! Nice build  

The 560W Seasonic is 80+ Gold, so I'd keep it. The only thing I'd definitely change there is a larger SSD. You can get by with 80GB-96GB if you don't mind occasional software uninstalls/reinstalls, but won't really avoid that unless you get something 120GB or larger.
The WD Black drive has the possibly unnoticed advantage of a 5-yr warranty, which is much better than the more typical two or three years their competitors are now offering. I think the Spinpoints are down to one year, so I will not buy another.
Edit: If you want to overclock, get something like a Xigmatek Gaia: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Thanks for the input. As for the SSD, I'm only planning to use it for the OS and maybe some main programs that I constantly use.