I wouldn't ditch your FX just yet. Well, not unless like me you are doing it just because you can really and for no other reason.
Intel are about to launch two mainstream desktop CPUs. One is a hex core, one is an 8 core. Once they do that they are going to have to get behind them and that means getting software devs to make sure they work properly. Up until now they haven't really bothered, but, they are going to want people to buy these CPUs.
Intel have all of the clout when it comes to stuff like that, so expect to see core usage rocket (you have AMD to thank for it really, due to the new consoles, but every one will think it was down to Intel and kneel before them as they often do).
Any way, you will see your CPU improve. You'll also see the FX 8s improve, due to the core support.
All balls to the wall an FX 8 is about as powerful as a 980x. It absolutely decimates the I7 920 when all of the cores are used. Ask yourself, do you need more power than that?
I just built a SBE rig running a 3970x with two Titan blacks. I also have an FX 8320 clocked to 4.9ghz with a 7990 and the only thing so far that I've noticed for my three grand is that I can play Crysis 3 absolutely maxed out with 8xmsaa (I couldn't before) and Watch Dogs stutters less than it did. Everything else = the same.
I would go with an FX 8320 with a good cooler. Clock it to 4.5ghz or more, then all you gotta do dude is put your hands behind your head, sit back and relax and wait for the core support to come. Once it does you won't need another CPU for gaming.
If you just fancy spunking some cash? then yeah, go for it. But if you value your cash and don't have it to just waste then go with the FX 8.
