Does anyone have any insight on why my single R9 290 never seems to submit as many shares as any of my 280x cards (GPU2 vs GPU0 and GPU1 in the screenshots below)? It runs very stable at 445Kh/s, but has about 20% less shares that the two 280x toxics I have running on the same rig at 387Kh/s. The 290 is still 10-15% lower in shares than some of my other 280s that run at ~360Kh/s. These are separate instances of vertminer running on the same machine, since I'm running 1 thread for the 290 and two threads for the 280s. Also, I'm currently mining EXE, but I use identical settings for VTC and have identical results.
toxics:
./vertminer --scrypt-vert -d 0,1 -g 2 -w 256,256 -I 13,13,20 --thread-concurrency 8192,8192 --lookup-gap 2,2 --gpu-engine 1080,1080 --temp-target 72,72 --gpu-memclock 1500,1500 --gpu-vddc 1.2,1.2 --auto-fan --gpu-powertune 20,20 --queue 2 --scan-time 5
290:
./vertminer --scrypt-vert -d 2 -g 1 -w 256 -I 13,13,20 --thread-concurrency 24550 --gpu-engine 1080,1080,1000 --gpu-memclock=1500 --gpu-powertune 20 --queue 2 --scan-time 5
I think it's because of the additional stale shares caused by running the 290 with a high work time (a side effect of high intensity). I'm not sure why that's not showing up in your WU rates here though.
The 290 can be run at a good hash rate with -g2 at low intensity by using sgminer and xintensity (in my experience, --xintensity 4 or 5, depending on make and model; TC will also vary).