I'm trying to use my ThinkPad W520 with external monitors in a docking station. When I start my computer with [Discrete Graphics] set in the BIOS, systemd loads and then the computer just hangs as if it can't find any screens. I've tried reinstalling with the latest nVidia driver, but that didn't help. I also didn't see anything out of the ordinary in Xorg.0.log. How might I debug this issue?If I change the BIOS to integrated graphics mode the login prompt displays on the laptop screen as expected. But since the external monitor ports are wired through the nVidia chip, I can't use my external monitors.journalctl | grep 'bumblebeed' reveals that it cannot find my nVidia graphics card.Nov 29 21:38:34 w520 systemd[1]: bumblebeed.service failed.Nov 29 21:39:34 w520 bumblebeed[1071]: [   75.407054] [ERROR]No integrated video card found, quitting.Nov 29 21:39:34 w520 systemd[1]: bumblebeed.service: main process exited, code=exited, status=1/FAILURENov 29 21:39:34 w520 systemd[1]: Unit bumblebeed.service entered failed state.Nov 29 21:39:34 w520 systemd[1]: bumblebeed.service failed.journalctl | grep nvidia gives:Nov 29 21:41:27 w520 kernel: nvidia 0000:01:00.0: irq 39 for MSI/MSI-XNov 29 22:47:04 w520 kernel: nvidia 0000:01:00.0: irq 39 for MSI/MSI-XDec 09 22:07:12 w520 kernel: nvidia 0000:01:00.0: irq 39 for MSI/MSI-XDec 09 22:12:44 w520 kernel: nvidia 0000:01:00.0: irq 39 for MSI/MSI-XDec 31 20:31:26 w520 sudo[19776]: wdkrnls : TTY=pts/1 ; PWD=/home/wdkrnls ; USER=root ; COMMAND=/usr/sbin/pacman -S xf86-video-modesetting nvidiaJan 16 18:01:58 w520 sudo[27554]: wdkrnls : TTY=pts/4 ; PWD=/home/wdkrnls ; USER=root ; COMMAND=/usr/sbin/pacman -Rscn nvidiaJan 16 18:02:10 w520 userdel[27699]: delete user 'nvidia-persistenced'Jan 16 18:02:10 w520 userdel[27699]: removed group 'nvidia-persistenced' owned by 'nvidia-persistenced'Jan 16 18:02:10 w520 userdel[27699]: removed shadow group 'nvidia-persistenced' owned by 'nvidia-persistenced'Jan 16 18:02:17 w520 sudo[27720]: wdkrnls : TTY=pts/4 ; PWD=/home/k ; USER=root ; COMMAND=/usr/sbin/pacman -S nvidiaJan 16 18:02:21 w520 groupadd[27758]: group added to /etc/group: name=nvidia-persistenced, GID=143Jan 16 18:02:21 w520 groupadd[27758]: group added to /etc/gshadow: name=nvidia-persistencedJan 16 18:02:21 w520 groupadd[27758]: new group: name=nvidia-persistenced, GID=143Jan 16 18:02:21 w520 useradd[27763]: new user: name=nvidia-persistenced, UID=143, GID=143, home=/, shell=/sbin/nologinJan 16 18:02:50 w520 sudo[27831]: wdkrnls : TTY=pts/4 ; PWD=/home/k ; USER=root ; COMMAND=/usr/sbin/pacman -S opencl-nvidiaJan 19 19:10:53 w520 kernel: nvidia: module license 'NVIDIA' taints kernel.Jan 19 19:10:53 w520 kernel: nvidia 0000:01:00.0: enabling device (0000 -> 0003)Jan 19 19:10:53 w520 kernel: [drm] Initialized nvidia-drm 0.0.0 20130102 for 0000:01:00.0 on minor 1Jan 19 19:10:53 w520 kernel: nvidia 0000:01:00.0: irq 41 for MSI/MSI-XJan 19 19:10:58 w520 kernel: nvidia_uvm: Loaded the UVM driver, major device number 245Jan 22 00:36:02 w520 kernel: nvidia: module license 'NVIDIA' taints kernel.The nVidia driver was working great until the beginning of december. Some of my attempt to fix it show up in the log.If I switch to Optimus mode in the BIOS and set Optimus OS detection to TRUE, then I am able to run optirun glxgears -info on my graphics card. 
nvidia driver [discrete graphics] on Optimus laptop doesn't load
arch linux;nvidia;laptop;multi monitor