Strange sound on shut down, Please help!

[1stXP]

This is a recent thing that I've noticed and don't know wheter I should worry or not. My computer makes a funny discharge kind of noise when I shut it down. It comes through the speakers and sounds like the capacitor in a camera flash that discharges really quickly when the power instantly cuts off. Any ideas what's causing this? I just got back board back from RMA and am not especially satisfied with this company anymore. I'm just waiting for it to die again and so I'm really paranoid. Please let me know if I should be concerned or not?
Thanks for your help!

 

[everman]

External speakers or system speaker? What kind of speakers, and do they use an external power source? it could just be your speakers but it doesn't sound like a problem with your pc...