A decent 990FX board (Asus SABERTOOTH 990FX R2) and a FX8320 or similar are fast. But, they do suck an awful lot of power and produce a lot of heat. I ran a
8320@4.5GHz and it was pumping out about 200W of heat.
Intel is a lot more efficient - a Haswell i5 will wipe the floor with the FX8320, but only uses about 35W.