I have a custom-built computer that was given to me, with a P4 processor, Intel D845PBET2 m/b, big case with multiple cooling fans, and honkin' big heatsink and fan on CPU. I recently experienced what appeared to be a thermal shutdown. I'd put this big case in one of those semi-enclosed cabinets (open in back) in a desk, and it got a bit warm in there. At the shutdown, I pulled out the case, found it to be quite warm. Mea culpa, should have known better. But it cooled off quickly and with enough ventilation it soon was back up and running. However the next day or so, I experienced another shutdown. This time restarting even when cold, it would not come up. Power to the box and the P/S is running, but otherwise no messages, and no output to monitor. In fact the monitor had a 'no signal' message, so the computer just won't boot. I suspected the heat got to the video card at first, but swapping cards didn't improve things. Now I'm suspecting the P4 is shut down. But is this a permanent damage situation, or is there a reset option? If I *promise* to keep it cooler, will it come back to life? Someone suggested that the heat may have dissipated the thermal grease and compromised the heatsink. And that I need only repaste the thing with Arctic Silver. Maybe, but getting the whole CoolerMaster fan and heatsink assembly off is not obvious, and I'm a little concerned that I might apply too little or too much Arctic Silver, generally make matters worse. Never having done this before, I only have the general idea. SO - is this likely to be the problem and a little heat paste will fix it, and that is within even my limited capability? Or is this CPU just toasted? Or am I somewhere in between? If this is a "leave it to the professionals" then I'll likely just start over with another system and move my working components over. The very moderate cost of a comparable system these days makes paying for expensive repairs not justifiable. Any advice would be greatly appreciated.