I am getting 1% or less rejects on f2pool with 3 1080ti rig. CPU usage is about 40pct on both cores: CPU Type   DualCore Intel Pentium G4400T, 2900 MHz (29 x 100). Have 12GB RAM and 30GB Virtual Memory on Windows 10. GPU utilization is 99pct on all 3.

Note that if anyone is going through MRR as a proxy you are going to get high rejects on grinmint - need to use f2pool it that's how you are configured.