Asus M2N SLIdeluxe, AthlonX2 6000, Antec TP3 650watt, Geforce 8600GT, 2x 1GB corsair, 500GB SATA, windows 7.
- Green LED on the mobo remains lit as it should.
- The computer powers on, power LED light up, fans spin, then the system shuts off. Then it will not respond to pressing the power button.
- My first attempt to move the computer case resulted in this powering on and off by itself. In the end I cannot explain this occurrence.
- I suspected the power switch wiring. After I metered out the switch and confirmed the switch and wiring was intact, I plugged it back into the Mobo and as soon as the plug touched the pin it powered on and off again by itself. I reaffirmed the power switch wiring was okay, yet it still will not respond to pushing it.
- I gave a single tap on only one power switch pin on the mobo (did not short the 2 power switch pins) with an isolated screwdriver tip and it again powered on and off. This is electrically equivalent to plugging in the open power switch which I did before. Maybe it responds to capacitance? Maybe I don't know what I'm talking about.
- If I try to power it on again right away it does not respond. I realized the system actually needs about 5 minutes or more before it will again respond to the screwdriver with powering on and off. If the power switch remains plugged in it never respond to pushing it.
- I can also get it to power on then off by connecting AC power to the power supply. As soon as power is connected it powers on then off by itself with no input from me. This method does not require the delay.
- Tried reseting the CMOS, did not work.
- Tried removing all RAM to get an error code, beeped once quickly before shutting off again.
- I read online topics and decided to check the PSU. I jumpered the power on pins and check every pin, every harness. Fan stayed on and all the voltages were in range of perfect.
- I tried minimal system build with either stick of RAM, no chassis fans. This did not fix anything.
- I then removed everything and visually checked for burns or damage. No apparent damage.
- This computer is a few years old. No previous symptoms before this problem.
- 500GB HD and Win 7 were both installed 6 months ago with no issue.
- The power switch is guaranteed not the problem.
- I don't think it's the power supply (650w), but is it possible that the voltage will drop under load and shut it down? I'd be surprised if my system used more than 350watts at any given time.
- I think it might actually be the motherboard, perhaps the circuitry is failing. Yet I find this strange because I generally don't hear of a motherboard suddenly stops working. My computers have always been reliable until now.
Thanks for reading, I'd appreciate any suggestions.