Over/underclock 5870 on Linux without limits?

Question

I want to downclock my ATI Radeon HD5870's memory to 300Mhz and overclock it's core frequency to 930Mhz. I can do this on windows using ATI Tray Tools.

On Linux, the only way to do this so far has been to use ATI Overdrive:

$ aticonfig --odgc

Default Adapter - ATI Radeon HD 5800 Series
                            Core (MHz)    Memory (MHz)
           Current Clocks :    850           1200
             Current Peak :    850           1200
  Configurable Peak Range : [600-900]     [900-1300]
                 GPU load :    97%

As you can see, the problem here is that it won't let you select anything that isn't in the "Configurable Peak Range", when it is entirely possible on Windows and perfectly safe to do so (within reason).

Do you know any way to set the required frequencies on Ubuntu?

Answer 1

You can unlock the limits downwards using AMDOverdriveCtrl. In the overdrive tab, set the Low, Mid and High values at 300MHz for memory. After that you will be able to use aticonfig to set memory clocks at 300MHz.

Answer 2

Despite what the "Configurable Peak Range" indicates, you actually can set a frequency outside of that range using Overdrive.

$ aticonfig --od-setclocks=930,300

Default Adapter - ATI Radeon HD 5800 Series
                  New Core Peak   : 930
                  New Memory Peak : 300

$ aticonfig --od-getclocks

Default Adapter - ATI Radeon HD 5800 Series
                            Core (MHz)    Memory (MHz)
           Current Clocks :    930           300
             Current Peak :    930           300
  Configurable Peak Range : [600-900]     [900-1300]
                 GPU load :    95%

This is with Catalyst version 12.1.