In one of my rigs, I get this problem that Windows get unresposive and slow. Have the error message unable to get fan speed - Unknown Error (999) as somebody reported before.

Tried lowered mem with no sucess and cards seems work in my test PC at 1000+ in mem OC.

Combo of GTX 1660 TI and RTX 2070.

Any ideas? Rig is working fine with other algos.