I’m trying to troubleshoot a failure to boot problem. The system is a Socket A AMD with an ASUS A7NX MB, Athlon ThrhBrd B CPU. This is a standalone computer that has never seen the internet and is not networked. A year ago I replaced the PSU with an Antec Smartpower 450w unit after I began getting the ‘reboot after shutdown’ problem. Replacing the PSU instantly resolved that problem. It began doing the same thing again a couple of weeks ago. Then, with a thunderstorm approaching, I decided to shutdown and completley unplug the system from power. (Yes, I have it on a ABS, but this was a BAD storm.) The next day I plugged everything back up but the system will not boot. When I turn on the PSU switch on the back of the computer it begins to power up before I even push the system start switch on the front of the case. I have disconnected the front power switch at the MB and the system still powers up when plugged in. I next disconnected the reset button at the MB and it still powers up (with both disconnected) when plugged in. The MB light comes on, the HDs spinup, the system seems to be repeatedly polling the CD and DVD drives and after 3 or 4 seconds it cuts the power completely and starts all over again, and again and again…… I hear no post beeps.
I cannot boot into safe mode. The only thing I have not tried that occurs to me is to pull the CMOS batt and see if it resets. Other than that I think my MB may be fried. What do y’all think? Any more tests to try before giving up.