Check the posts in the Hardware section. I know in one of them, frodocooper, posted Canaan's documentation on
"extra options" for clocking. Personally, on a hot day 90°f and above, my 841's push ~14TH/s with no adjustments.
However, they also draw more power as a result. Goodluck!!!
Edit: it was this thread. Ha!!!
https://bitcointalk.org/index.php?topic=2616205.msg37085708#msg37085708thanks for linking. I saw the commands but assume it is a combination of commands like adjusting voltage and frequency. I need to setup a test machine and try some.