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#1
PC Shuts Down Unexpectedly During Start-Up
Hello everyone!
I need your help with my PC. It just shuts down itself after between 2-30 seconds everytime I turn it on. There is no BSOD or any beep. This is what I did for the couple of hours:
1. Disconnect all connected loads from PSU except the 24-pin, and the 8-pin for CPU. I run the PC but still shuts down.
2. Disconnect the PSU from the case. Test is using the "paperclip" method; all voltages are within the limits (+/-5% for 5v and 3.3v and +/-10% for 12v). Connect a chassis fan to the PSU then run continuously for a couple of hours. PSU does not shuts down. (I dont have a spare PSU so I cannot replace it to check..)
3. Clean all parts, up to the disassembling the CPU, then reassemble. Still shuts down. (I dont know if CPU itself is OK, i have no way to check it..)
4. Reset the CMOS and replace a new one. Still have problem.
5. Rearrange the RAM modules; use each one (I have 3) for each slot (my MoBo has 4 slots) but still shuts down. I also removed all RAM then run. I expect a beep but it didnt have any single beep when turned on.
6. I disconnect all cables connected to MoBo except the Power SW and SPEAKER, thinking that there is shorting. Still have problem.
7. I put insulations (cardboard) between the mounting bolts and Mobo and between MoBo and the nut under the MoBo (dont know what it is called). Still no luck.
8. I then decided doing something more "risky". I run the PC as usual, and as expected, it shuts down. But I didnt turn off the PSU, instead I removed the 24-pin from the MoBo. Then I wait some 10 seconds and reconnect it to MoBo. The chassis fan which is connected directly to PSU (as I said in 2) thru Molex runs and then shuts down. And then again, I removed the 24-pin without turning off the PSU, and then perform AGAIN the paperclip method (dont worry, I am somewhat "brave" in handling a DC system.) and then check the supply the voltages in each pin and they are all OK. I also noticed that at the time I removed the 24-pin from the MoBo, the chassis fan suddenly runs.
My conclusion as of now is that my MoBo is faulty.. Am I correct? That last test I did was proof that the PSU does not shuts down because of "over or undervoltages" because I think you cannot remove that type of alarm from PSU without turning it off, so I am somewhat convinced (60%) that PSU is not the problem.
Please instruct me on what to do next in order to fix my problem..
Thank you very much, guys!