What is the max safe miner temp for the Apollo II?
As with most of my miners and other computer related circuit boards, my personal experience has shown the upper limits to be an average of 74c. Anything higher and I start seeing erratic behavior including lock-ups and shutdowns. Operating higher than 74c-75c and you run the risk of damaging your equipment or at the very least shortening it's lifespan considerably. My personal preference is to keep everything in the range of 67c-72c with short term spike limits of 73c. This works for me.
I appreciate the input. I understand this works for you, but it doesn't actually tell me the specifics of the PCB max or Chip max temp, which I'd like to know. You must understand that 73 is quite cool for some silicon, such as current AMD processors (95) and most ASICs, and frequently ASICs go much higher than general purpose CPUs.
BITMAIN publishes data for their miners showing PCB max values in a range from 75 to 95, with Chip max values up to 135.
https://support.bitmain.com/hc/en-us/articles/360005088914-Miner-Normal-Operating-Temperature-RangeMax PCB temps should be under 80c, the silicon in our ASICS can handle 95+
PCB autocuts power once temps go over 83c in case there is something wrong with the fan/controller...we have mutiple failsafes on these and cut no corners since these are run in homes.
With that said running in turbo mode or max currents on any electronic device will shorten its lifespan.