How to fix "Warning!! System resets due to over-clock..."?

Try clearing the CMOS. To do this open the case and look for the CMOS reset jumper pins and move the jumper over, try to boot it will fail, then move it back and try to boot. If you cant find the jumper, then unplug the computer, remove the battery on the motherboard, then hit the on switch a few times which should drain any remaining power in the capacitors and clear the CMOS. replace battery, plug in and try it.