If you want to run your farm headless, and manage it through SSH, you will soon discover the dreaded: "aticonfig: This program must be run as root when no X server is active" or "ERROR - X needs to be running to perform ATI Overdrive(TM) commands" error messages.
To monitor temperatures (or any other aticonfig command) you need the following:
user@farm:~$ export DISPLAY=:0
user@farm:~$ xhost +
access control disabled, clients can connect from any host
user@farm:~$ aticonfig --adapter=all --odgt
Adapter 0 - AMD Radeon HD 6900 Series
Sensor 0: Temperature - 90.00 C
Adapter 1 - AMD Radeon HD 6900 Series
Sensor 0: Temperature - 103.00 C
Note, you can use any of the aticonfig commands to tweak clock settings or whatever.