I've come across a problem with Dell Inspiron 7500s. I've seen this about half a dozen times now. You power it up and the fan kicks in, then it shuts down. Then it starts up, then shuts down, and cycles like this again and again until you remove the power sources. I've replaced motherboards and the problem persists. I've replaced processors and the problem persists. I've tried it with the memory taken out, with the hard drive removed, with the video card removed and various combinations and permutations. Nothing changes. Even with a brand new motherboard and processor, the same thing happens. Has anybody seen this and does anybody know of a fix? The guys at Dell tech support haven't been any help; they just keep sending new parts.