Well my case is the Antec Nine Hundred Two, and I'm using the stock fans supplied with it. I forgot to mention that, thanks for reminding me! So that's one large fan on top blowing air out, and 2 smaller ones in the front blowing air in. The GPU has its own cooling fans of course, and the PSU also has one. It's not like I replaced those or did anything special, so I didn't mention anything about those fans.
I added a Hyper 212 EVO to the CPU to accomodate the slight overclock (and because CPU stock fans are a little wonky sometimes).
The PSU now works well in my GPU-less system, but like I said before, I'm unsure what caused the GPU to selfdestruct in the first place. If the PSU is still fine I'll happily keep using it, I just don't know how to check that before I put a new 500 euro card in...