For some reason setting fan speed with either GWE or nvidia-settings fails on OpenSUSE Tumbleweed. If I run nvidia- settings with the -V switch I see no errors in the terminal when attempting to set a fan speed.
I have this in /etc/X11/xorg.conf.d/52-nvidia.conf
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "NVIDIA GeForce GTX 1070"
Option "Coolbits" "4"
EndSection