What wifi card do I need for this motherboard?

That is kinda strange motherboard for one claiming to be for gaming....then again almost all try to claim that since it means nothing.

You really only have 1 slot and I will assume you are putting your video card in it. There are pci express wifi cards but the selection it not real large.

I would go with a USB based wifi card and use a usb extension cable to move it away from the case. Which you choose will be based on your router and the internet connection. You do not want to buy a real fancy one if your router is basic. You want to avoid the very tiny USB devices, the size of the internal antennas does make a difference.

....as a added comment you do not really want to use wifi if you rally plan to use the machine for games it is too inconstant in performance.
 
It would work I guess, I have never put one in a small pci express slot.

Just be sure to have the antenna facing your router. If you put it under a desk against a wall you will block your signals from most directions. This is the main issue with internal cards, they have nice big antenna but they are located very close to the metal case.