X99= extreme rendering and high workloads > gaming, Z97=gaming> Extreme rendering and high workloads.
In short the X99 is not worth buying for gaming, get a good quality mobo like ASUS Z97-A, Extreme4, or Z97X Gaming 5 with a 4690k and overclock it + a good gpu like gtx 970 and you are set to max out nearly any game at 1080p