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Unexpected drop in GPU core clock on C60 APU

Question asked by blu on Sep 22, 2013

Hi,

 

I've been using two C-series APUs in tandem for benchmarking and unit-testing of proprietary OGL/OCL software. The APUs are running Ubuntu Oneiric installations, which even though not identical, have been kept largely in-sync for the purposes of development - same kernel versions, same Catalyst/fglrx versions, same compiler toolchains, etc. Now, one of the APUs is a C-60, and the other is a C-70. Everything has been going smoothly until a few days ago when the C-60 started exhibiting an abnormal performance degradation - all my benchmarks started showing a performance gap between the two units. Poking around I noticed that the GPU core clock of the underperforming unit (C-60) was below its nominal value:

 

$ aticonfig --init --odgc
Uninitialised file found, configuring.

Adapter 0 - AMD Radeon HD 6290 Graphics
                            Core (MHz)    Memory (MHz)
           Current Clocks :    200           533
             Current Peak :    275           533
  Configurable Peak Range : [275-275]     [533-533]
                 GPU load :    0%
$ aticonfig --init --pplib-cmd "get clock"
Uninitialised file found, configuring.
Engine Clock Range: 200-200 MHZ; Memory Clock Range: 533-533 MHZ;

 

In comparison, its sibling C-70 has been running all normal (both systems are running on AC power):

 

$ aticonfig --init --odgc
Uninitialised file found, configuring.

Adapter 0 - AMD Radeon HD 7290 Graphics
                            Core (MHz)    Memory (MHz)
           Current Clocks :    275           533
             Current Peak :    275           533
  Configurable Peak Range : [275-275]     [533-533]
                 GPU load :    0%
$ aticonfig --init --pplib-cmd "get clock"
Uninitialised file found, configuring.
Engine Clock Range: 275-275 MHZ; Memory Clock Range: 533-533 MHZ;

 

(the recurrent use of --init flag and corresponding 'configuring' message is due to the absence of xorg.conf on either system)

 

My efforts to get the core clock of the 'slacking' unit back to 275MHz have been fruitless. Perhaps because I have no idea what caused the drop in the clock in the first place. Any ideas for getting the 'ailing' unit back to full speed, or what could have causes the drop, would be greatly appreciated.

 

Regards,

Martin

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