Need help from a computer nerd! AMD changing FSB?

I have an old elite mobo (ECS 760gx-m) S754. It came with a 1.6gh cpu which i replaced today with a 3400+ 2.2gh AMA3400BEX5AR. The computer recognized the cpu as the 3400+ no problem, it even recognizes the 1mb L2 cache. It was still operating at 1.6gh so I changed the FSB to the max allowable 255 (from 200). problem is it is only operating at 2039MH instead of the 2200mh it should be. My software (everest home) says its overclocked 27% wtf! I dont know much about pc tech so if any suggestions to get my cpu closer to the 2200mh would be appreciated.