What resolutions do you plan on playing at?
This system should run any game on the market (save Crysis 3) completely maxed out at 1080p. I'm sure you can get Crysis 3 to run on high, but maxed out will be trouble.
A few things to note in this build:
1) 990fx chipset motherboards aren't necessary for mid end gaming builds. You would be able to save some money by getting a 970 chipset. They run about 80-110 USD.
2) 750 watts is extremely overkill for this system. While you would be safe with as low as 430w, I would suggest something around 500-600w. Also, Corsair HX series are excellent PSU's, but you can go cheaper and still get an excellent unit. Try looking at Corsair TX units!
3) The Sapphire version of the 7870 ghz has an excellent aftermarket cooler, and is currently the cheapest 7870 on the market. (184.99USD@Newegg.com) I would suggest getting this card over any others.
Only things I can see to make it better would be to either purchase an FX8350 (about 80 dollars more) and maybe an upgraded GPU. If you have any sort of budget or simply are not an enthusiast, this build is probably as good as its gonna get