I use two 5870 for mining. With the last days being quite warm in Germany they are getting quite hot. I found, that ATI is quite clever by lowering the clock rate if the GPU is getting too hot. It seems this happens if the GPU is going over 92°C. However the clock rate decreases to the peak ranges minimum (600 MHz on this cards) and increases to the max peak range (900 MHz) a few seconds later. Giving some kind of yoyo-effect. After some time it wont recover from 600 MHz even if the temperature falls significantly.
For this reason I hacked a "Quick and Dirty"[tm] shell script which I can use as a cron job. Each run it iterates through the cards, checking their temperature and in- or decreases the clock rate for a given amount (25 MHz in my case) until the temperature stabilizes between 85° and 90°C. It does this for each card seperately as my cards have different temperatures.
Now I have two questions:
1. Is the temperature (85-90°C) okay for this GPUs in the long run? Or should i consider lower temperatures?
2. Is anybody interested in this code? I could put it somehwere. My hope is that this script gets better over time if more people use it and contribute. But i think it wont make any sense to put more work into this piece of code if nobody is interested. Perhaps it makes sense to flesh it out becoming a real daemon which also handles starting and stopping the miners. Furthermore it could make sense to shut down mining if the room temperature goes above a defined threshold.
I guess this is of no interest for heavy overclockers or people with air conditioning. But i hope for people like me using their desktop PC in a normal home office it might be of interest. It'll give maximum stable performance which is great if you just want to "fire and forget" your miners without the need for checking the temperature hour for hour as the temperatures raise. Just enjoy the summer with your family instead of worrying about the miner temperature
This is a sample output from syslog:
May 9 01:04:02 newton mining-supervisor: card 0 at 84.50 C - Below threshold. Dethrottling from 850 to 875 MHz
May 9 09:05:02 newton mining-supervisor: card 0 at 90.50 C - Above threshold. Throttling from 875 to 850 MHz
May 9 11:11:01 newton mining-supervisor: card 0 at 89.50 C - Within safe range (85-90 C) running at 850 MHz
May 9 11:11:01 newton mining-supervisor: card 1 at 83.50 C - Below threshold but card is already at full speed (900 MHz)