It's a nice build! However, I made some changes:
- You need an SSD, there is no way around it.
- Changed the CPU cooler. The CoolerMaster 212 Evo is a fan favorite. Low noise, great performance... and cheaper !
- Changed the hard drive. Western Digital BLACK are better.
- You don't need a Network adapter. Your motherboard already has 2 Ethernet ports, and your internet connection won't be anywhere near fast enough for it to make any difference. Also, it's more complicated to setup that onboard LAN and has less features.
- I wouldn't get that case, but I'm guessing you put it there because you like it so I didn't change it.
- Changed your power supply. A great bargain. 760w, 80+ Platinum... and at that price ! Plus, it's a Corsair.
- Noctua NF-A14 are great case fans. Good choice !
- Changed your GPU manufacturer. I've had only bad experiences with Zotac and Sapphire, and so did my friends. I don't buy from them anymore. Also, Asus' STRIX is just plain better and at a very low premium. There is a good argument to be made about going for a GTX 970 instead. I'd do it myself, but the 390 has 8gb of VRAM and is marginally better overall...
For 100$ more, you have a infinitely better system. I'd get it in a heartbeat!
http://pcpartpicker.com/p/yDGJFT
Good luck and good hunting !