SirNightShade :
dontlistentome :
The CPU is only one piece of the puzzle. I don't know what you hope to accomplish but I can tell you that simply upgrading to the fastest CPU your motherboard can support doesn't always solve the problem. Sometimes the 'fastest' is still too slow, if the tech is behind the times.
commented specs
It looks like you could stick an FX 8350 or 8370 in there. That'll take you from 3.6ghz to 4.0ghz. Like others have said, there's no point to that. You already have an FX 8xxx series CPU, so you're already getting the most out of your system from a CPU standpoint. You still haven't said what it is you're trying to accomplish. Until you specify what you need an upgrade for, it's hard to suggest anything useful.
edit: For example, if I say "I want better performance" that's kind of vague. What's 'better'? Performance in what?