As @sizzling said, the question is more what games you will be playing, & what resolution you will be playing at. Sure, an i7-4790 can handle a 980Ti (& even SLI a pair of them), provided there's enough juice from the PSU...but unless you're planning on gaming at 1440p or 4K resolutions, that 980Ti is going to be overkill. Even at 1080p resolutions, the Tom's Hardware recommendations only range from the 950 to the 970 (with the 960 comfortably in the middle), or AMD's 280s/380s as alternatives. Heck, if you're not even going to reach 1080p resolutions, even a 970 would be overkill.