HOWTO install Nvidia's proprietary driver in ExTiX 15.1 64 bit version 150104
2. Create a new initrd with command: update-initramfs -c -k 3.16.0-21-exton
3. Restart your computer
4. Log in as root and run command: chvt 1 && service gdm stop
5. Log in as root in console mode and run command: init 1
6. Run command chmod 755 NVIDIA-Linux-x86_64-340.65.run
7. Run command: ./NVIDIA-Linux-x86_64-340.65.run --no-unified-memory
Follow the instructions during the installation. Answer NO when asked about DKMS.