I thought PPS Sieve had high GPU usage so I didn't bother checking it on my 1080Ti but it was very low even with CPU crunching stopped. 7:49 with 1 task. 9:06 with 3 tasks.
Even on the 1070 and 1070Ti they were around 10:40 and 9:18 at 2x. When at 3x they were running at 16:00 and 13:00. Improvements there too.