I'm kind of embarrassed to admit that it's taken this long, but I may have solved the cooling problem atlas has had for the past couple years. Without the case open and a fan blowing in, the machine just shuts down. It used to be sporadic, but lately, it's a step away from instantaneous.
A few months ago, I noticed that using the integrated network controller or the amd76x_pm
patch exacerbated the shutdown problem. These are functions of the southbridge. Sure enough, the Tyan Tiger MPX
has no cooling at all on the AMD 768 southbridge chip (big chip next to the 3rd and 4th PCI slots from the bottom).
In April, I bought a new EPoX motherboard for another system which came with a huge bag of goodies, including a small bag of mini heatsinks. So, I dug them up and popped a bunch of 'em onto the southbridge. I made sure there was airflow from the intake fans by shuffling PCI cards and moving a hard drive, and then closed it up. So far, there have been no shutdowns with the case on, surviving 85F room temperatures at night.
I have had one linux crash (not a shutdown), but I am almost convinced that it's because of linux's temperature sensor support or the notoriously unstable amd76x_pm patch. With those disabled, I have had no further problems.