Both the i5 and i7 will work fine with it, but, if you plan on upgrading graphics or adding in SLI in the future go with the i7. The i5 could definitely handle 980 Ti SLI, but you certainly won't be getting your full money's worth. Definitely don't go for one of the everyday consumer i5 chips. Probably should't step down to Devil's Canyon either unless you can find an epic price, as, while they are only 20% different in power, Skylake is much more flexible and utilizes DDR4, as well as a revamped microarchitecture.