Download the latest compatible bios for your motherboard and follow online instructions of how to add this to a usb flash drive.(make sure that is the only file on the flash drive) Remove the ram, cpu and graphics card. Plug in your flash drive to the white usb connection at the back of the board (this is the flash bios). Nowturn on the system (you don't need a display) The usb and motherboard flash bios will blink on hte motherboard. Wait untill usb/motherboard stops blinking. Turn off system. Now re-install cpu, 1 stick of ram, and graphics card. Boot system. If all is ok, add the rest of your ram.
Sometimes the bios won't update with the cpu installed if there is a compatibility issue with the cpu. There shouldn't be, but this is worth a try as I know several people have cured this following this procedure.
Let me know how it goes.