The build looks good overall. The 7870 is very close to the GTX 660 and I can run BF3 on ultra settings @ 60 fps on a 1920x1080 resolution. The system you are setting up is very close to what I am doing. Good luck with your build and enjoy! I am running Windows 8.1 right now and I am very pleased with it.
Windows10, Antec EA650 Power Supply, Acer XB270H G-synch monitor, MSI Krait Gaming 3X, I7 6700K, 16 gigs of CORSAIR Vengeance LPX DDR4 3200 MHz ram, HyperX 3K 240 gig SSD, MSI GTX970