Hi, I've got a Dell Studio 540 desktop (sitting on a carpeted floor) that I use for graphics rendering work. I have a second Studio 540 sitting next to it. One of them works absolutely perfectly, running fast and more importantly running silently. The other, however, is displaying some irritating behavior. Its fan will start, stop, start, stop, and so on in a precise pattern, over and over again; it will run for about ten to fifteen seconds, then shut off, and then repeat the cycle. It's