See if your mobo version is the 2.0 or if you have the 1604 bios version on you pc , if not you need to download the M5A99X EVO BIOS 1604 : http://www.asus.com/Motherboards/AMD_AM3Plus/M5A99X_EVO...
Select your os and download the bios.
It's easy to do, there are plenty of guides/videos of how to.
Then you can put any of those cpus in the mobo without worries.
I'd go for the fx-6300.