Installing Debian on Kaby Lake machine: difficulties with X.org

For Kaby Lake (and any Intel graphics since Broadwell), you need to install a new kernel and firmware from Jessie backports; as root:

echo deb http://http.debian.net/debian jessie-backports main contrib non-free > /etc/apt/sources.list.d/jessie-backports.list
apt-get update
apt-get -t jessie-backports install linux-image-amd64 firmware-misc-nonfree

You also need to remove (paradoxically) the X.org Intel video driver (as indicated in the package description: the X server can use the kernel’s mode-setting features without a separate video driver):

apt-get remove xserver-xorg-video-intel

When you run this, if apt-get tells you it’s going to remove other packages, don’t let it do so; you might need to install xserver-xorg-video-dummy to satisfy dependencies.

You should also remove the kernels you installed manually.

Once all that’s done, reboot and you should find your system working much better.

If that fails though, you can try installing the backported Intel driver instead (along with the new kernel and firmware):

apt-get -t jessie-backports install xserver-xorg-video-intel