K20 GPU Operation Mode support

One of the nifty new unsung features of K20 is the ability to set the GPU Operation Mode (GOM) to be compute only, allow low precision graphics, or full graphics. This is a power saving option since disabling the graphics functions may lower chip power use.

Unfortunately this mode is only controllable with K20m, not with K20c. This is mentioned in
library API documentation.

Neither the K20c or K20m has video out, but the graphics hardware could still be used for offscreen rasterization. (I can make high resolution shadow maps for volumetric raytracing, for example.)

But why is changing the GOM mode restricted for K20c but not K20m?

I know nothing about GOM, but the second message in this thread seems to suggest the situation may be more complicated than what you decribe:

https://devtalk.nvidia.com/default/topic/525927/?comment=3722280

Could you point me to the exact document that mentions GOM?

It’s an option in nvidia-smi. It’s discussed in a bit more detail in the NVML API documentation, section 7.2.2.6 on page 26.

https://developer.nvidia.com/sites/default/files/akamai/cuda/files/CUDADownloads/NVML_cuda5/nvml.4.304.55.pdf

Thanks also for that forum post link. That’s similar to the problem I’m hitting. But the question is why the option to change this mode is disabled? And why it is not on K20m, which is effectively identical.

I would echo the question; Why have it controllable on the K20m only?