I am trying to fix a computer for a colleague of mine, I am having all kinds of problems with it. Let me start with the beginning: My colleague told me he had a computer (Asus A7V mobo, AMD Athlon 900 MHz, 512 MB SD-RAM) from his parents-in-law which has all kinds of problems with starting up. He got blue screens at random times, the computer occasionally didn't start up at all etc. He took a peek in the BIOS hardware monitor to see what kinds of temperatures the system generated. Well, it turned out the CPU was running at 90+ degrees Celcius (that is almost the boiling point of water for you who use Fahrenheit), so there was something seriously wrong. He gently vacuumed the inside of the case to get rid of all the dust that has been accumulated over the years, but that had no effect. When he brought it to me the day before yesterday, I took a peek at the CPU fan, which was clogged up with burned up dust (judging from the bad smell and brownish color). The fan was literarely stuck, so I had to jank it loose and I tried to rub all the dust off with a dry cloth and a vacuumcleaner. When I had cleaned off must dust from the fan, I placed it back onto the CPU, attached the cables back in the mobo and hit the power switch. I heard fans, harddrives and a cd-rom (I forgot to took out of the player) spinning up and waited for the POST screens to appear on the monitor. Nothing, just nothing. I checked the CPU, it was very hot and when I looked at the fan, I knew why, the fan didn't spin at all. It just stood still, waiting for ... something. I took the fan + heatsink out and tried connecting it to another computer (Intel) and it immediately worked liked normal. So there is nothing wrong with the fan. I brought in a spare fan, just in case, but again, nothing on the AMD, but it worked on the Intel. Time constraints forced me to take the computer home, I would have a look today. Today I disconnected all drives, cards etc (including RAM and videocard) except the CPU and the heatsink + fan combination. I plugged in the mobo-power connector, powered it up. The PSU-fan turned on, the harddrive turned on, the standby-light on the mobo was on, except for the CPU-fan. I tried connecting the plug to the CPU fan to the chassis-fan connector on the mobo, but still nothing. This little rolleyes: ) story leads to one question: What can I do further to test the system? I don't have a spare mobo and CPU for testing, I only have the stuff which was already in the case. I reset everything to default (all jumpers and dipswitches. Also the BIOS, which I reset to default before the computer meltdown), so there just can't be something wrong in the settings. I am afraid the CPU is fried, but there can also just a simple setting I missed. The CPU itself looks OK (no burn marks for as far as I can see), but the socket does have little black burn marks.