Hi. I really do need help on my PC (Acer T120; AMD Athlon XP 2.4GHz, 768 Mb 333DDR RAM). I have had it for 2 years now. The 6 months are fine then the chassis fan started to make noise. Soon the the CPu fan join in and then a month later, the CPU fan died and the Chassis fan was fine and has no noise anymore. When Cpu fan died, the PC shutdown within minutes after starting. However, it was under warranty then and I sent to Acer Repair Centre. It stays there for 4 long months! The reasons, I was told, mobo is defective and need to order from Taiwan. New mobo also found defective had to order another one. So finally it came back but it occasionally hangs (freezed and need to cold boot). At the repair centre, the CPU fan was replaced. Soon a year is over and there is no warranty. Well, it usually hangs after using it over night. So I gave the PC its daily rest for a few hours. It seems to be fine otherwise. 1.5 years passed, one day, the PC failed to start with message "boot disk not found". So I opened up and did come checking. I found that one of 2 IDE slots is not working (the one connected to hd) and the other slots connected to CDRW seems fine. So I got myself a RAID card and the PC were fine again as the HD is then connected to the RAID card. It works fine but then the CPU fan started to make noise again. Again it started to sudden power off when the CPU fan slows down or stops. So I got myself a replacement CPU fan. The original noisy CPU fan is a 70x70 mm 12V DC fan, 0.6A with 5100 rpm speed and the new one was less speed (3000rpm) and no amp stated. The new fan is AMD authentic fan (AMD brand). CPU fan is connected to a 3 pin port on the mobo. I also got myself a 4 pin connection exhaust fan (at the PCI slot) to improve cooling. I have another 4 pin power supply port free. The chassis fan is also connected to a 3 pin port on the mobo. The chassis fan is 90x90mm fan with 12C and 0.32A, speed 3000 rpm. All rpm are detected using speedfan. The operating temperature is 35C for mainboard and 38C for CPU before the CPU fan was replaced. When I replaced the CPU fan, the chassis fan started to make noise. The operating temp is 31C for motherboard and 37C for CPU. When the chassis fan make noise, it slows down and occasionally stop. When this happened, the PC will power off (switch off). I could not start the PC again. I need to wait for some time, I do not know how long but sometimes 30min sometimes more then only I can start it back. Sometimes the PC can run overnight when I make sure the chassis fan run without noise. The chassis fan is buggy, it will make noise during start up but if I touch it with my finger at the middle a few times, it may reduce it and after a while it may be going. The PC will run fine for hours. This can only be done when the PC is started up with the case open. If it is closed and if I ignore it, it will power off and will not start again until after some time. However, when I start it again, the fan will make noise. So usually, I start up and try to remove the noise manually. I tried to get a new fan but a 90x90mm chassis fan usually have 4 pin connectors and when I got one, the PC will not start when I tried it by connecting the new chassis fan to a free 4 pin power supply and left the 3 pin port on the mobo unplugged or free. When I plugged in the original fan with 3 pin connection connected to the 3 pin port on the mobo it starts but with noise again and the same noise removal procedure is needed. If anyone has any idea about the problem with my PC, or how to fix it, I would be very happy and will appreciate it very much.