I'm not a gamer but if I was to build a gaming rig it would be in an ATX case with an Atx mobo. Ease of installing hardware. I would also buy the mobo with compatible CPU and ram as a bundle . The SSD as C drive is ok but the second drive I would use a 7200RPM 64MB cache drive instead of a hybrid, but I state again I'm not a gamer.
Best of luck to you anyway but you might find a better response from the Games forum.