Different possibilities for this..
Often it's a CPU/socket problem...i.e. CPU is not seated well in the socket or bent pins in the socket. Reseat the CPU and have a good look for bent pins and if there are none, then reseat the CPU carefully making sure that whatever cooling solution you are using' you mount it very carefully and with even pressure.
The board might have a problem...is it new to you? or you had it a while
It's also possible that the memory controler on the CPU has a problem
Have you done basics like flash latest BIOS or reflah BIOS,,,,change BIOS chip....clear CMOS etc.?