There are two things you can try to do:
1. Cross test the CPUs. if you have two, use only one (you will need to close the other socket with a terminator, these are relics so may not be an option).
2. in the BIOS processor submenu there is an option called 'Processor Retest'. Select Yes and then save and reboot the board. Se if the error is cleared and the boards works ok.