Some longer interval tests...
My 970/750ti test rig (linux, quark algo, 0.1 diff) reports ~27M with -g 3 setting now. It was 19M without -g parameter. But yaamp reports lower hashrate! It is about the half of the hasrate reported by ccminer. (13M vs 27M)
when you build yourself you need to make sure that you have compute5_2 in the makefile. Compute 5.0 will cause invalid hash on compute 5.2 cards for some reason.
nvcc_ARCH = -gencode=arch=compute_50,code=\"sm_50,compute_50\"
nvcc_ARCH += -gencode=arch=compute_52,code=\"sm_52,compute_52\"
You also suggested to lower the priority. I reduced the nice level by 5 (from 0 to +5) but same performance.