There are some valid points 4 both cases. I own the HAF X and have been pleased with the air cooling. With 2 480s in sli, the gpu fan shroud keeps them from getting too warm.
If you're putting the gpus on water, then from what I've read, the 800D would seem better.
My setup had 1 480 originally, and the thing could be touched even after an hour of running Prime 95.
Now I installed a high flow gpu fan, rated @ 90 cfm @ 16dbs, so that worked really well.
We all know how these #s are suibjective at the best of times, but the usb3/sata3 hot swap bays and enhanced cooling straight out of the box was what sold me 4 air cooling.
Whichever way u go will be just fine and it really depends on your preference, so good luck and enjoy!
