In theory, yes. In reality that's not true. How do you know that you don;t have a ground fault issue with the wiring. most people do not check their outlets and there are plenty of outlets in the US that are not wired correctly, been gnawed on by rats, or just fail over time. As well, here in the very dry SoCal, you can still shock a pc and do damage. Even if it is properly grounded. BTDT numerous times at the company I used to work for.

Well, Art I want to thank you for this thread. I was in the wife's office today and noticed a loud humming sound coming from her desktop. I remembered this thread and decided to open it up. Sure enough, the fans were coated with dust. I'm not sure why since its in a clean room in the house but for some reason that room collects more dust. Anyway, I blew out the crud and its back to being quiet as usual.

Reminder to everyone: Be sure to blow the dust out of the power supply as well as the cpu fan.

Joe,
I think it's the dust and carpet fibers that get pulled into the PC when the carpets are vacuumed and pets (at home, not the office). We used to have a pet rabbit in the basement, where my PC is and it used to get rabbit fur all over the inside of the case, especially if the tower sits on the floor, which most of them do. Glad I was able to help by reminding people to clean up their PC's!