On Wednesday, March 09, 2011 10:48:29 am m.roth at 5-cent.us wrote: > Lamar Owen wrote: > > Heat and airflow are two others. > Hmmm... has the a/c been changed lately? Or maybe stuff outside the rack > been moved, and so obstructed the airflow? To followup a little, I had a motherboard one time, with a factory-installed CPU, heatsink, and fan, that would not run for more than four or five hours before hanging. This motherboard was in a system that was donated to us as being 'flaky' so I don't know the warranty status or what the original owner had or had not done, but it did have a factory seal sticker strip between the heatsink and the CPU and the motherboard socket, and that sticker was tamper-evident type, and there had been no tampering. I decided I would refresh the heatsink compound, and, since even if it were still covered by the warranty that would have only been valid for the original purchaser. So I pulled the sticker strip, which left little 'voids' on things, and pulled the heatsink. At that point I laughed so hard I cried, as the heatsink still had the clear plastic protector film between the CPU and the heatsink compound. From the factory. I pulled the film, reinstalled the heatsink, and that system is and has been for several years rock-solid stable. The issue of dust buildup follows from the heat and airflow. There is another potential culprit, though, especially if this system has been in a raised floor environment, that some might find odd. That culprit, or, rather, those culprits, are zinc whiskers. Also, the metal components in the electronics themselves can exude whiskers; see the wikipedia article on the subject for more information ( https://secure.wikimedia.org/wikipedia/en/wiki/Whisker_%28metallurgy%29 )