sudo add-apt-repository ppa:graphics-drivers/ppa is not needed anymore, since Ubuntu 16.04 added tested and working NVIDIA Drivers long ago.
And using the lastest drivers, or compiling that "binaries" from NVIDIA webpage will spoil your system because they are not tested by the Ubuntu team. So using
nvidia-381(as far as I know is the newest driver released) is not recommended and It may cause you an infinite loop black screen.
So I will recommend you to do the most and eficient secure method.
For making sure what driver your system needs.
That command will tell you what packages you will need for using NVIDIA drivers.
Then just make sure to install this
sudo apt-get install intel-microcode
sudo apt-get install nvidia-xxx
And that's all, note that I told you
nvidia-xxx because you must enter the driver version displayed in
ubuntu-drivers devices and I warn you updating the kernel may cause you problems, so once you installed that NVIDIA driver, please don't upgrade anymore, for updating just use
sudo apt-get upgrade that command will hold new kernel releases.