CPU: AMD athlon II x4 630
Gfx: NVIDIA GTS 250
RAM: 4gb Gskill 1066mhz
Windows 7 x64
This rig is pretty old now but I don't really want to go for a whole new mobo/CPU/RAM combo if I can avoid it. The main goal is to be able to play Diablo 3. I'm not expecting ultra graphics but it would be nice to have a nice frame rate (40fps+) at 1920x1080 on lowest settings.
So I know that my CPU is a piece of crap and according to Gigabytes site my motherboard supports the new FX processor. I have read somewhere that putting an FX CPU into an AM2+ motherboard doesn't give the best results
Am I better off getting a Phenom II x4 980 or something from the FX line. I am also interested in getting a decent cooler and over clocking the crap out of it
To be perfectly honest, I would try your hand at overclocking your CPU and upgrade your video. You have a quad core so it shouldn't fair to bad with games. Strap a good $25-$30 cooler on it and crank it up a little. Most games are GPU intensive and that is where you gain your FPS and ability to turn up details.
While you can do better (e.g. with a 955BE), your CPU isn't exactly "crap." Most likely your GPU is the most notable thing you'd want to upgrade. What you can get will depend largely on your PSU. Assuming it is a quality 450W-500W unit, you'd have no trouble with a GTX560 or a HD6850.
Well, check the brand to be sure; if it has a little voltage switch, subtract 100W to 150W to be safe. If you're left with 450W as a realistic maximum, you can handle a HD6850 or GTX550Ti. If 500W is realistic, then a HD6870 or GTX560Ti should run on it. If it really is 600W, then pretty much anything you want, possibly excluding the HD6990 and GTX590.