Wait, I thought the i7-7700k could only use memory up to DDR4-2133/2400
Not really, but I did use the cougar fans instead of the stock ones. I moved one of the stock ones to the back radiator and am going to add another back in on the bottom to push out the extra gpu heat. I'm not a huge fan (pun intended) of stock fans and usually replace them with silent ones. Without getting scientific, it looks like they're about the same size. Although I remember something about a vertical rod that I just strait up pulled out of the rig because I had no idea wtf it was for, and it was causing trouble. I'm having no issues w/o it, so it must have not been important. Hope that helps.
Looking back it was a mistake. I should have gone for the 900 series, but at the time of building (May 2014) I had just gotten my job and didn't have the money saved. I felt like the 770 was a good HIGH level class between the premium cards and the mid-level cards.
I added another one to try and compensate when I also upgraded to the 4K display.
Short answer, you're right, the 900 series would have been better. If I built it today, I would use a single 900 series.