Modules loading despite being added to the blacklist

Solution 1:

After modifications in /etc/modprobe, you need to run:

sudo update-initramfs -u

I would be careful with disabling drm etc. I wouldn't be surprised if the nvidia driver depends on it (check with modinfo nvidia). Also, should you have any problems with your nvidia driver, then you will have a low resolution screen which might not support the GUI login at all.

Why would you disable the iGPU? The processor is already in use so I doubt if it saves any power or resources.

Solution 2:

In a similar situation to the OP, and heeding all of @Lekensteyn's good advice, blacklist i915 silently appeared to do nothing for me, even though lsmod said nothing was using i915, but install i915 /bin/false did the trick, causing Gnome 3 to automatically fall back to using llvmpipe.