To be honest, as I've mentioned before, I've not had the greatest experience with 7.6 or 8.1 at any temperature. 7.1 is rock solid for some reason. I would recommend trying 7.1 on your machine to see if you have the same kind of stability issues. If not, then it's the OS. If so, then it's a matter of CPU cooling (or power supply).So, Spicy O'clockers in the Northern Hemisphere, how are your machines handling warmer ambient temperatures? Before we finally broke free of near freezing temperatures in the early morning hours, the room where my machine lives, would see ambient temps below 20C. Currently, with daytime highs fluctuating between 24/32C and my house thermostat set to 25.5C during waking hours, the ambient temperature is ~24C in this half underground room. For the past month, I have been doing some programming, which has me using the machine for some hours a day. Ten or so days ago, my LC475, overclocked to 49mhz and running System 7.6, would start to go unstable after an hour or so of use. CPU temps would be getting close to 50C as would the inside of the power supply case. The power supply seems to be the culprit, as there is no fan to dissipate the heat. My solution has been to remove the top cover and run a small fan, blowing on the side of the power supply. This keeps the internal temperature down to the low to mid 30's. I can run for hours with no stability issues at all now. The CPU runs about 10C degrees cooler with the case off (fan installed on heatsink), but if I don't run a fan onto the power supply, it eventually warms up enough to start causing stability issues again.
I'm not the most adept tinkerer, but perhaps I could extend the power lead wires, to where I could move the power supply outside the case, as running without the cover on is less than ideal!