1st, if it isn't for 4k its overkill, I would wait, try your single and then decide if the games you play require another one. Does it have to be EVGA? Zotac has the AMP! (non extreme). It's the cheapest non-refernce Cooler 980 Ti, it has stock clock speeds, I have to warn you, I have it and its massive almost didn't fit in my DeepCool Tessaract case, I had to put it in diagonally then straighten. You can mix and match as long as they are all 980 Ti, mixing clock speeds has changed, it used to go to the lower cards speed but now its supposed to manage the load based on each clock speeds. From what I've heard this works sometimes but sometimes hinders performance, but I'm sure it will get better!