I have a PC for about almost 4 years already. It has Gigabyte motherboard ga-m68sm-s2l, and AMD Athlon64 x2 5200 SKT AM2 Dualcore. In the past, sometimes (not always) it stopped at some step (always the same step) during booting before starting Windows. But a few days ago, it just broke down itself suddenly while it was working. It couldn’t boot itself and had nothing displayed on the screen when I tried to power it on. Then I unplugged the its power cable, after a few seconds I plugged it in and powered it on again, it booted alright, and the started Windows. But the next day, it suddenly broke down again. This time it won’t boot it anymore no matter what I tried. I have tried disconnecting the power supply of DVD, HD and CPU. What I found is that after I unplug and plug in the power cable of the PC, it will start the PC power supply’s fan, the PC case’s fan, and CPU’s fan, then the power shuts down immediately, and the 3 fans stop spinning. If I don’t unplug the power cable and directly try to turn on the PC, usually the PC won’t even have any reaction, just like dead, not even start the fans! Later I found if I just disconnect the ATX 12V connector, after powering on the PC, the 3 fans will work fine and keep spinning, i.e., the power supply will stay, it won’t shut down itself immediately like before, unless I switch the power myself. I’ve also measured the voltage of the power supply to ATX 12V, it’s 11V. I don’t know if the 11V is the problem or actually it’s just because my meter didn’t give accurate read. Anyone knows what exactly the problem is caused this? Is there a problem with the PC power supply or the motherboard (for example, even the ATX 12V connector on the motherboard)? Anyone had the same issue before and how do you fix it? Thanks very much.