NVIDIA drivers installed - but not in use on Ubuntu (Studio) 16.10

Question

After searching for possible solutions and trying many different things without any success, I decided to ask the community.

I recently built a computer containing a GTX 1050 ti. After installing Ubuntu Studio 16.04 and installing NVIDIA drivers (before they were not shown in the additional drivers list), I tried to play 'Kerbal Space Program', but the performance of the main menu and the start up process of the program were very slow.

I couldn't see the NVIDIA drivers in the Additional drivers tab of settings application, but after adding some other repositories, I finally now can see these three drivers options there: Additional drivers

I tried both of them in my subsequent test glmark2. Both times GL_RENDERER was displayed as Gallium 0.4 on llvmpipe. From my online research (and the glmark2 score of 291), I figured out that the NVIDIA drivers are not being used, even though the NVIDIA drivers were selected in the list of Additional drivers. Here are the outputs from lspci -vnn | grep VGA -A 12 and lshw ->

lspci -vnn | grep VGA -A 12
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GP107 [10de:1c82] (rev a1) (prog-if 00 [VGA controller])
Subsystem: NVIDIA Corporation GP107 [10de:11bf]
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at f6000000 (32-bit, non-prefetchable) [size=16M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
Memory at f0000000 (64-bit, prefetchable) [size=32M]
I/O ports at e000 [size=128]
Expansion ROM at 000c0000 [disabled] [size=128K]
Capabilities: <access denied>
Kernel driver in use: nvidia
Kernel modules: nvidiafb, nouveau, nvidia_375_drm, nvidia_375

lshw -class display
*-display                 
   description: VGA compatible controller
   product: GP107
   vendor: NVIDIA Corporation
   physical id: 0
   bus info: pci@0000:01:00.0
   version: a1
   width: 64 bits
   clock: 33MHz
   capabilities: vga_controller bus_master cap_list rom
   configuration: driver=nvidia latency=0
   resources: irq:16 memory:f6000000-f6ffffff memory:e0000000-efffffff memory:f0000000-f1ffffff ioport:e000(size=128) memory:c0000-dffff

Answer 1

Disable the nouveau drivers - to do it open a terminal and execute the following command :

sudo nano /etc/default/grub  

Add nouveau.modeset=0 to this line -> GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

that it now reads -> GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nouveau.modeset=0"

Press Ctrl + X to close the file and confirm the change you have made by pressing Y.

Now update the GRUB boot configuration to make this setting active : sudo update-grub

Reboot the operating system, now you use the NVIDIA drivers and nouveau is deactivated.

Update addressing your comment that Gallium 0.4 on llvmpipe is still shown :

Keep the GRUB boot configuration change you've made.

Boot the computer and uninstall the NVIDIA drivers ...

When the login screen appears press Ctrl+Alt+F1.
Enter your user name and the password, then execute :

sudo apt purge nvidia*
sudo poweroff  

Boot the computer and re-install the NVIDIA drivers ...

When the login screen appears press Ctrl+Alt+F1.
Enter your user name and the password, then execute :

sudo apt update
sudo apt install nvidia-375
sudo reboot