Make sure your BIOS is updated to the latest version...
if the version it has does not support your CPU, it will not work correctly.
Make sure it is not getting to hot and down clocking itself (i use http://www.alcpu.com/CoreTemp)
If the BIOS settings and version check out, and the temperatures are in the correct range, then maybe its a bad chip. If you had another motherboard to test it on thats awesome, but most people don't have the luxury.