Yeah I've noticed strange sounds out of my (older) computer, too. For instance, during heavy processing I can hear the fan speed change. However with a lot of computers (older ones because they are old, and newer ones because they are made of cheaper materials) some kind of interference will occur, I don't know if it's an electrical field or what but it causes sounds to come out of your speakers, particularly when graphics are being updated, but this varies from computer to computer because components are located in different places. For instance, one computer I had would cause a buzzing sound whenever I would minimize/maximize and window, and a different sound when I would drag it. My very new dell laptop actually has already developed this problem, however in this case I think it's something other than the graphics card. I've seen this a lot but can't offer much of a solution for it.