Hi Bob,
First of all, I am not aware of what I have done regarding settings in photoscan to reach this, I was sort of lucky I guess.
Also, many phases of the whole workflow still work without using the GPU, unfortunately.
Also, I have heard sometime GPU's can go into some sort of selfprotect mode where they will run at 324 mhz untill you restart the computer. Don't push the GPU to the limit I would think. Keep the voltage a bit low.
I backed up from trying to overclock things. Pushing the limits seems not to good for the stability and it is fine to me if a job runs 200 hours instead of 180 hours, if that means the machine will not crash.
At night, when the small room where the computer is located is closed, I even run it at a lower CPU multiplier. Does not seem to affect the time to finish.
My first question would be to start GPU-Z and look at the VREL at the second tab, that often tells a lot. If it is THRM the GPU's are just running hot.
I do know the pcie of my motherboard is still running at 2.0 speed according to GPU-Z, but it might be totally unrelated.
So look for the businterface speed in GPU-Z, it should not be at 1.1 when under load and maybe you can get 3.0.