Ubuntu only uses the Intel graphics driver for ONE login

Question

I switched to ubuntu 16.04 from Win7 about a week ago and am quite happy so far. However, contrary to what I read on the ubuntu wiki and other ressources the graphics of my Unity desktop ran on the nvidia graphics card rather than the intel-integrated graphics card (which should be the default). When switching to the intel card via nvidia prime I wasn't able to boot at first, but it worked after installing the latest intel graphics driver with Intel Graphics Tool and booting with nomodeset.

Unfortunately, the machine didn't boot with the intel driver but with the fallback VMware llvmpipe driver which made everything really slow. To properly use the laptop I have to switch back to sudo prime-select nvidia again but this makes my battery only last half as long as it did with Win7 and the machine also overheats pretty fast.

When deleting the nvidia drivers again and running on nouveau I could switch to the intel driver (it was even default, just as it should be) and it WORKED! However, this allowed me to login only ONCE. After reboot or logout the screen freezes after the next login attempt. I can only move the mouse and need the RSEIUB shortcut to restart and go back to nvidia.

Short summary for those, who found the writing above too confusing: I wanna use my intel CPU to process the graphics. With nouveau it does, but only for the very first login. Afterwards I can't login anymore. When installing nvidia proprietary drivers and nvidia prime it doesn't work at all and I can only boot with nomodeset which makes the machine use the llvmpipe driver instead of the intel driver making everything extremely slow.

I don't know what else to do. Apparently, nobody else had this issue and people usually only complain about nvidia drivers. So, any help is very much appreciated! I am a utter noob so I have no idea about altering driver blacklists etc.

Processor: Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz

Graphics: NVIDIA Corporation GM206M [GeForce GTX 965M] (rev a1) and Intel(R) HD Graphics 530

nvidia driver: 384.111

Using the intel microcode firmware

my output to lspci -knn is

00:00.0 Host bridge [0600]: Intel Corporation Sky Lake Host Bridge/DRAM Registers [8086:1910] (rev 07)
Subsystem: CLEVO/KAPOK Computer Skylake Host Bridge/DRAM Registers [1558:0152]
Kernel driver in use: skl_uncore
00:01.0 PCI bridge [0604]: Intel Corporation Sky Lake PCIe Controller (x16) [8086:1901] (rev 07)
Kernel driver in use: pcieport
Kernel modules: shpchp
00:02.0 VGA compatible controller [0300]: Intel Corporation Skylake Integrated Graphics [8086:191b] (rev 06)
Subsystem: CLEVO/KAPOK Computer Skylake Integrated Graphics [1558:0152]
Kernel driver in use: i915
Kernel modules: i915
00:14.0 USB controller [0c03]: Intel Corporation Sunrise Point-H USB 3.0 xHCI Controller [8086:a12f] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H USB 3.0 xHCI Controller [1558:0152]
Kernel driver in use: xhci_hcd
00:14.2 Signal processing controller [1180]: Intel Corporation Sunrise Point-H Thermal subsystem [8086:a131] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H Thermal subsystem [1558:0152]
Kernel driver in use: intel_pch_thermal
Kernel modules: intel_pch_thermal
00:16.0 Communication controller [0780]: Intel Corporation Sunrise Point-H CSME HECI #1 [8086:a13a] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H CSME HECI [1558:0152]
Kernel driver in use: mei_me
Kernel modules: mei_me
00:17.0 SATA controller [0106]: Intel Corporation Sunrise Point-H SATA Controller [AHCI mode] [8086:a103] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H SATA Controller [AHCI mode] [1558:0152]
Kernel driver in use: ahci
Kernel modules: ahci
00:1c.0 PCI bridge [0604]: Intel Corporation Sunrise Point-H PCI Express Root Port #3 [8086:a112] (rev f1)
Kernel driver in use: pcieport
Kernel modules: shpchp
00:1c.3 PCI bridge [0604]: Intel Corporation Sunrise Point-H PCI Express Root Port #4 [8086:a113] (rev f1)
Kernel driver in use: pcieport
Kernel modules: shpchp
00:1f.0 ISA bridge [0601]: Intel Corporation Sunrise Point-H LPC Controller [8086:a14e] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H LPC Controller [1558:0152]
00:1f.2 Memory controller [0580]: Intel Corporation Sunrise Point-H PMC [8086:a121] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H PMC [1558:0152]
00:1f.3 Audio device [0403]: Intel Corporation Sunrise Point-H HD Audio [8086:a170] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H HD Audio [1558:0152]
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel
00:1f.4 SMBus [0c05]: Intel Corporation Sunrise Point-H SMBus [8086:a123] (rev 31)
Subsystem: CLEVO/KAPOK Computer Sunrise Point-H SMBus [1558:0152]
Kernel modules: i2c_i801
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GM206M [GeForce GTX 965M] [10de:1427] (rev a1)
Subsystem: CLEVO/KAPOK Computer GM206M [GeForce GTX 965M] [1558:0152]
Kernel driver in use: nvidia
Kernel modules: nvidiafb, nouveau, nvidia_384_drm, nvidia_384
02:00.0 Network controller [0280]: Intel Corporation Wireless 3160 [8086:08b3] (rev 83)
Subsystem: Intel Corporation Dual Band Wireless AC 3160 [8086:8070]
Kernel driver in use: iwlwifi
Kernel modules: iwlwifi
03:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device [10ec:5287] (rev 01)
Subsystem: CLEVO/KAPOK Computer Device [1558:0152]
Kernel driver in use: rtsx_pci
Kernel modules: rtsx_pci
03:00.1 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 12)
Subsystem: CLEVO/KAPOK Computer RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [1558:0152]
Kernel driver in use: r8169
Kernel modules: r8169

Answer 1

Unfortunaetly i do not have the same processor as you but my Intel NUC5-i3 does not have any problems with his onboard gpu at all. I did not install any other drivers exept those I could choose from the "Software & Updates" window. I would not expect your CPU nor faulty Linux drivers as cause. I suppose there is some missconfiguration. Check lspci -knn what kernel drivers/modules you could use with your graphics card. Then have a look at

ls /etc/modprobe.d/ and less /etc/modprobe.d/blacklist.conf Maybe you are blacklisting some default graphics driver. Once i had this problem because of using nvidia proprietary driver.

Also check Yannicks answer at Can't get Intel HD Graphics 530 (Skylake i7 6700) to work :

I'm on msi gs70 6qe with i7 6700hq and GTX 970M.
With Ubuntu 16.04 LTS installer USB stick, using UEFI, I've finally booted 
successfully !
The only boot parameter I've set after the "splash" parameter was 
"nouveau.modeset=0".
To me the Intel HD 530 works fine but not the NVIDIA GTX 970, which freezes 
Ubuntu's boot process. Probably a NVIDIA firmware will need to be 
added/uploaded to avoid boot freeze.

Reading thru the page you have posted I found https://01.org/linuxgraphics/downloads/intel-graphics-update-tool-linux-os-v2.0.2 :

Ubuntu* 16.04

Due to a known issue with Ubuntu* 16.04, third party applications cannot be
launched automatically via Ubuntu's package manager. Ubuntu* 16.04 users must
install the gdebi tool which will enable them to successfully run the Update
Tool. See the following link for detailed instructions:

Running the Update Tool using gdebi

and also:

Known Issues
[...]
Using the Ubuntu* Software Center (or the "apt" package manager) to uninstall 
the Intel® Graphics Installer for Linux* will not remove the 01.org "apt" 
package repository. To remove the repository, disable the repository in the 
Ubuntu* Software Center using steps described on the Ubuntu wiki
[...]

One more thing to add: If you have one or more free USB flash drives: You could use them to test different OS (Ubuntu 16.04, Lubuntu 16.04, Mint etc.) without installing them on your machine, just to see if the problems you experience persist.

Answer 2

Thanks for the extensive response!

I looked into all the files in /etc/modprobe.d/ and when on nvidia only the nouveau and lbm-nouveau drivers are blacklisted while on nouveau no graphics driver is blacklisted. On both nvidia and nouveau the intel microcode module is blacklisted with The microcode module attempts to apply a microcode update when it autoloads. This is not always safe, so we block it by default. as comment.

Also lspci -knn didn't show anything unexpected, I've put the output into the question.

Adding "nouveau.modeset=0" into my grub file, however, seems to have done it! I have booted 3 times without a problem now and hope it stays this way.

When using the intel update software i followed their instructions with gdebi, actually.

The only issue is that I have to go with nouveau now, which is fine as long as I don't need proprietary drivers for something special (e.g. for a 2nd screen). Anyway, thanks for the help, it really was a big step of progress!