(In reply to poma from comment #43)

> There is no the GPU fan here, so I tested the CPU fan, and this is how it
> works:
> /etc/udev/rules.d/10-cpu-fan-manual-mode.rules
> RUN+="/bin/sh -c '/bin/echo 1 > /sys/devices/platform/it87.656/pwm1_enable'"
> 
> Therefore remove ACTION & ATTRS part, so it runs unconditionally.
> 
> Before you reboot, check with:
> # udevadm trigger

Now my 10-...rules files in /etc/udev/rules.d/ looks like this:
RUN+="/bin/sh -c '/bin/echo 1 >
/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/hwmon/hwmon1/pwm1_enable'",
RUN+="/usr/local/bin/nvapoke e118 80000002"

During boot, it sounds as if it gets triggered several times
(noise-silence-noise-silence), but it ends up with a silent gpu fan when the
graphical desktop has started.
Startup logs are flooded with messages like:

nvapoke:473 conflicting memory types e8000000-f0000000
uncached-minus<->write-combining
reserve_memtype failed [mem 0xe8000000-0xefffffff], track uncached-minus, req
uncached-minus