AboutRider Expertise With 20 years experience I can answer almost any question about Intel computers ror build, restore, backup, configure, OS problems, Hardware issures. Setup of hardware components, repair, remove and replace. Trouble shooting hardware/driver issues.
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Experience I have been a hardware/os tech for over 20 years, I also own a web site for the do it yourselfer with over 170 articles.
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Question I built a PC for my son about 3 years ago. He is into gaming and uses the machine quite heavily. Recently he needed to upgrade his video card and used his Christmas money to buy a new one. When I installed it for him I noticed that both PSU fans as well as the chassis fan and CPU fan would continue to run well after the machine was powered down (sometimes for almost a full day). I thought I did something wrong but he said it was doing this before I installed the new card. I fully cleaned the system of dust but no change. I put it on the list of things to get to and he continued using the machine for a couple of weeks. Yesterday after shutting the machine down he found it would not restart. No beeping motherboard or hard drive spinning up, etc... I noticed the fans keep on spinning and I checked all the PSU voltages I could get to (i.e. +12V, +3.3V, +5V) and they seemed to be within the appropriate regulation limits. The power switch works. Same issue if I put the old card back in so I don't think its video related. I suspect both issues are related somehow. Any ideas? Its probably the PSU or the motherboard. Can a faulty PSU cause all the fans to stay on? I was thinking motherboard issues keeping the PSU, chassis, and one of the PSU fans to stay on but I didn't think the motherboard controlled the main PSU fan. Anyway, any ideas would be helpful. I was thinking of changing the PSU because I would really like to avoid changing the motherboard. He just spent $170 for the AGP video card and changing the motherboard would mean not only scrapping the motherboard but also scrapping the new video card since everythings gone to PCIe... Thanks for your help.
Answer If all the fans are conrtolled by the motherboard, that is the power connectors are on the motherbaord then the thirmistor (a tempature measuring device, usually under or very close to the processor) has failed.
The thirmistor thinks that the tempature of the motherboard and processor are high or have not dropped when you power down the computer.
You could try setting the temp control in the BIOS depending on the BIOS publisher and the motherboard manufacture if you have that type of control. My old ASUS P4B motherboard had that but the new ASUS P5K doesn't, just voltage control.
You could try changing out the Power supply, may want to go to a higher wattage. (This would be the cheapest route, be aware that the newer motherboards use the ATX 28 pin power cable for the motherboard, yours proabably has a 24 pin cable).
If it is the motherboard (which I suspect) you can still find motherbaords that accept AGP video cards, for a while PCIe and PCI-X were the rage but I noticed when I upgraded my computer that the AGP slots were making a come back.
