The goal

For the time being, I want the nvidia GPU to be off at all times. I purchased a dGPU laptop only because the non-dGPU motherboards of the T460s seem to be affected by a design flaw and will eventually cause spurious reboots when a module of RAM is installed. Note that it is not guaranteed that the dGPU mobo are not presenting this flaw.

The issue

Apparently bbswitch worked a while ago. Now it is a bit unclear if it actually works or not. To sort things out, let me first update to the latest kernel. This appears to be

Linux bl4ckspoons 5.8.9-gentoo

On startup it seems to turn the card OFF, provided that /etc/modprobe.d/bbswitch.conf reads as follows

options bbswitch load_state=0 unload_state=-1

Notice that dmesg still complains about the following warning

ACPI Warning: \_SB.PCI0.RP09.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20200528/nsarguments-59)

This appears to work, at least on the first suspend cycle. I should double check with powertop if the power consumption is actually low