What's with all the expansion cards?
Wireless sure, though you could by a motherboard with integrated WiFi. You don't need another network interface it already has a 1Gbps Ethernet port. Sound card is somewhat redundant as well, unless you are after quality, in which case you need to spend more.
4x4GB memory kit isn't necessary. 2x8GB would be more stable and use less power. Also leaves room for expansion later.
You should buy Windows 8.1 rather then 8, basically 8 is out of support and you would have to upgrade anyway. Which means installing the OS twice essentially.
A single GTX970 will tear through any current title at 1080p, should do very well even at 1440p.