This is my build. Any advice?

my only advice is use 2x 4GB ram and Radeon 270 (much better than gtx 660)
this will be a good full AMD build

btw why dont you include any HDD in the build?

you can pick 1TB and downgrade the GPU to 260X

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: AMD Athlon X4 760K 3.8GHz Quad-Core Processor ($84.74 @ Amazon)
Motherboard: Gigabyte GA-F2A88XN-WIFI Mini ITX FM2+ Motherboard ($107.99 @ Staples)
Memory: Kingston Black Series 8GB (2 x 4GB) DDR3-1600 Memory ($69.99 @ Amazon)
Video Card: HIS Radeon R9 270 2GB Video Card ($187.14 @ Amazon)
Case: BitFenix Prodigy (White) Mini ITX Tower Case ($69.99 @ TigerDirect)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($49.99 @ NCIX US)
Total: $569.84
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-02-26 10:14 EST-0500)
 


Sorry , i have an SSD and HDD.
The reason i went with the 1 8gb stick is for upgradability. The R9 270 price has skyrocketed lately and i dont think its worth it