I wrote a complete article on how to install drivers and cuda for RTX 2080 series GPUs on Ubuntu, mainly because it can be a time consuming task for some(most?) users. You are advised to follow the article along with the following answer.
I observed the same issue with both Ubuntu-16.04 and 18.04. In Ubuntu-16.04 the machine hadn't found the correct Nvidia driver and it had been using open source Nouveau display driver. Hence you're required to download and install the proper driver from Nvidia.
Now install the drivers as follows.
1) cd Downloads/
2) ls
#(NVIDIA-Linux-x86_64–410.57.run #output of ls)
3) chmod +x NVIDIA-Linux-x86_64–410.57.run
#(to get permission to execute the run file)
4) sudo ./NVIDIA-Linux-x86_64–410.57.run --no-x-check
Note: --no-x-check flag is important. Otherwise you will have to disable the x-server and log out from the GUI.
Once the drivers are installed reboot the machine and verify the installation with nvidia-smi command on a terminal. It will show you GPU and installed driver information.
The next part is installing cuda which can be a pain at times. You will have to log out from the GUI and perform all the actions on a terminal.
Download your relevant cuda run file from this link. Then create a file called blacklist-nouveau.conf in your home directory and add following lines to this file.
blacklist nouveau
options nouveau modeset=0
Now we have to log out from the GUI by pressing (ctrl+alt+f1) to install cuda. Enter your username and password to go to the terminal.
Now follow the steps below.
1) sudo service lightdm stop
2) sudo -i
3) sudo cp /home/avin/blacklist-nouveau.conf /etc/modprobe.d
#change avin with your user name
4) sudo update-initramfs -u
5) exit
6) cd Downloads/
7) md5sum cuda_10.0.130_410.48_linux.run #(Optional)
8) sudo sh cuda_10.0.130_410.48_linux.run
Cuda installation wizard will appear. Follow apparent steps, along with the article.
Once the installation is finished run reboot on this terminal.
Once the machine is rebooted add cuda path to the .bashrc.
1) sudo gedit ~/.bashrc
2) Add following 2 lines at the end of the .bashrc file
export PATH=/usr/local/cuda-10.0/bin${PATH:+:${PATH}}
export LD_LIBRARY_PATH=/usr/local/cuda-10.0/lib64${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}
3) source ~/.bashrc
Now run nvcc -V on a terminal which should yield an output as follows.
installation message
Now that the drivers and cuda are installed you might want to install tensorflow gpu version. Here is a good tutorial for the very same task.
Best Answer
Make sure you are using the NVidia proprietary driver. Then installing nvidia-opencl-dev and nvidia-opencl-icd-xxx where xxx correspond to the driver version you are running should be fine. That worked for me on 16.04