GPU load is only 10-15%
But I asked for CPU not GPU ^^
By the way: you did not use the hotfix ... you are running on AMD? Then I would recommend to use optiminer, that one is faster for AMD right now. For Nvidia you should add the --enable_nv_hotfix, because else it is likely that 6 GPUs will cause a lot of load and a segmentation fault - unless you have some Ryzen Threadripper or Intel equivalent in that system.
It' s my error, CPU load 10-15%. Not amd, my system: i7 7700 + gtx1060x6.