Disclaimer: The following text is copied from http://www.astahost.com/info.php/Pc-Fan-Spins-Stops-Bootup_t10844.html. I am facing the exact same problem, for which there is no solution posted in the site above. So guys anyone with a suggestion/solution? My board: ASUS A8N-E RAM : 512 MB DDR HDD: 2x 80 GB [1 Sata, 1 Pata] GPU: XFX nVidia 6600 PSU: Zebronics I just want someone to confirm this before I go online and buy the part (which is probably going to be expensive). --> --> Just took a look at my cousin's Acer (ASUS) Pundit computer. It's one of those small form factor machines. Well, I pushed the power button and the power lights up for one second and shuts off immediately. I popped the little critter open and watched the fan spin for one second and then stop. I have to unplug the cable and replug it back in, in order to push the power again to see if turn on for one second...nothing. My first guess was power supply...then I used one of my power supply testers on that 20 pin (I think)power cable and the fan started to spin...no problem there This is my first time using a power supply tester, but I assume that means it's definitely NOT the power supply. So right now, I'm guessing is has to be the motherboard right? Like I said, I want to make sure this is the correct piece to get since it will probably be expensive since this machine is not that old (about a year only). Not sure how I can test out a motherboard to be sure it's not faulty (like using power supply tester for power supply testing), so if anyone has ideas on how to do this, I'm all ears If it helps, the ethernet port is lighted up when the power cord is plugged in...but I don't think that means anything. Board probably still bad? Thanks.