PCA Forums

About 10 sec after shutting down my comp, a low decible, high pitch humming starts down. As soon as I power up, it goes away. It seems to be coming from the motherboard .I cannot isolate it exactly but it is not coming from the system speaker. When I wiggle the ethernet card, the sound wavers slightly. It is the bottom slot on the MB. Everything works fine, just that annoying hum
is not a fan! sound like a tubirne or something like that.

There's still power to the motherboard when it's turned off. Some things (like the LAN card) keep running.

I can't see how the LAN card would make any noise - there's just no parts on it that would do that. However the power supply can make a whining noisy when the computer is off (I especially notice this on the cheap PSUs that come with E-Machine systems).