The first and second machines were top of the line motherboards. After that, I switched to "el cheapo" motherboards. At the time I was in Vegas with my garage routinely getting into the 110-120 degree range for extended periods at both day and night. Yes, I have not been kind to my computers. I have since moved and am looking into a new computer for my mill, which again is in my garage (also un-airconditioned as before). I have a few computers to choose from since I've blown so many motherboards while living in Vegas and want to not repeat that problem, although the temperature here is much cooler so it might not be a problem anyway. Maybe my solution will be half a dozen fans pointed at the motherboard for peace of mind. The problem seems to only happen at the worst time, right in the middle of a long job but isn't that always the case?
Thanks to everybody on this forum for all of the help.
-Andrew