Fans run after power down

I had some problems with my pc suddenly freezing. I suspected a virus perhaps. No virus. Went into bios( I am sure that I did not change anything but...) and all seems fine. Prior to the computer freezes, I had installed net frame work and SP3 beta. I uninstalled these programs. Now the computer seems to be stable and runs well. My problem is that the fans continue to run after power down. I have to unplug the power cord to kill the fans. Any ideas?
I will supply more info about the pc if necessary for a diagnosis. BTW, this is a new mother board, KT-400 and the problems began about 3 months after install.

Thanks in advance!

Bill

 

Fans running sounds like Stand-By Mode. There may be a setting in your OS for Hibernation that could make you go into hibernate when you hit shutdown. Right click a blank spot on the Desktop and select Properties then Screen Saver and then Power. On the advanced tab does it say "when I press the power button on my computer" shutdown or does it say Standby. Under the Hibernation tab is it enabled? You want shutdown for the power button and disabled for hibernate to prevent the fans from running.

 

I will check the settings this evening. Thanks!

 

I went into bios last night. It appears that the system is set for shutdown. The system does not come back up by pressing any keys or moving the mouse. I did make a couple changes in bios to see what would happen(I wrote down what I changed) and same thing, fans continue to run. Could SP3 beta have screwed this up?

 

Another thing to consider is the fact you installed a new motherboard. Even if it took a few months to occur if your system is an OEM (HP/E-Machines/Dell) and you replaced the motherboard but kept the OEM power supply that could be your problem. Often OEM parts are proprietary (that only can be replaced with ones from the maker) So an OEM supply on an non'OEM Motherboard could mean some comnnections are not exactly correct.

I would expect the system would not work at all or would fail immediately not 3 months later, but it might be a good idea to try another supply if you can. It might just be coincidence that the supply failed at the time you were playing with Dot Net and SP3.

If your old motherboard failed, and thats why you replaced it, it maybe it failed from a spike from a failing power supply and that needs replacing too. If you replaced it as an upgrade and the old one is ok that scenario is unlikely but I would still try and borrow a supply from someone to test. If it still happens with another one then you know its the board, heck you might have bought a defective board and its still under warranty.