I would go with a water cooler but the problem is my case is too small (SG10, mATX) and I don't have room for the 120 mm radiator. It has to be an air cooler. I think I can push my card to 1600 Mhz if I had adequate cooling and modded BIOS.
You can use the TITAN ACX COOLER on your gtx 980ti. They come with the top plate to help cool the front VRAM And VRM. It's easy to install, too. But, like I said, you still need proper cooling on the back of the card. EK backplate works. I'm not sure if the eVGA backplate actually helps cool or just for aesthetic.

