It's been years since I had this computer and I've done some upgrades so far. I bought a modular PSU from Corsair that's at least 750 watts (Corsair TX750M) and I bought a CPU that fits in my socket perfectly which is the AMD Athlon 64 6400+ @ 3.2 GHZ but now I need a GPU that can run games in 1080p in at least High settings. I was thinking of getting the Zotac Nvidia Geforce GTX 660 (which I assume could probably fit in my case) but I really don't know if it would be compatible considering that my motherboard is pretty well damn old. Any recommendations or ideas? I'd be willing to spend at least $150-$350 for a GPU upgrade.