I have just built a computer for my mum. Its all fine apart from when you shut it down and it turns off, It humms quite loud I think it is coming from the main board. Is there something I need to disable in the bios?

Many Thanks

PS - Also after cheap HP Printer Cartridges if anyone can help.

I have this problem too but its the monitor that hums when in standby. It is annoying isn't it?

Mine is definatly the board and when I turn the PSU off at the back to stops.

Look for the settings in BIOS which keeps Cooling fans ON even if computer is switched OFF (Soft-Off) by Windows. In this case your motherboard gets power from the PSU to cool down the components using Fan(s). You can try out with one thing though.... Make a boot disk and start the system through floppy. Goto DOS prompt or just Boot Menu for that matter. Then manually switch off the system using POWER button on your cabinet. If there is no hum then you win.. else you will have to change some BIOS setting.

Also see to it that there are no CDs in your drives while shutting down the system.

BTW, which mainboard you are using ?

Its not the fans that are on its more of a humming noise. Its not the PSU as it came from another computer that didnt have this problem.

As there are no other moving parts on mainboard... it sounds impossible that the board is producing hum noise.

Sounds like electric going through a transformer. Really wierd.

Oh man... then believe me its your power supply. Try for the temporary replacement just to be sure.

AC current going through a coil or transformer or capacitor may cause it to resonate (vibrate) in the audible range. Try loosening or tightening screws or shifting things around to stop the humming. For humming TV's and computer monitors dropping some hotglue on the flyback transformer would sometimes work. ...the basic idea is to change the physical properties enough that it doesn't resonate.

what will the settings in bios look like or say to keep them on?

Its in the Power Management section. But in last 5 years I have only seen it on one board made by some third party from Taiwan.