This bug has been reported at  launchpad.net, #163915
My notebook is a HP Pavilion 17-g164ng with an AMD A10-8780P APU.

The sytem (Ubuntu 16.04.2, kernel 4.8.0, UEFI) does not work when not booted
using workaround parameters:


nomodeset: resolution 800x600
nomodeset xforcevesa: 1600x900 (optimal resolution)
amd_iommu=off: "boot finished" sound within a minute, black screen, ssh login
possible
no parameter: no boot, no (remote) access, no dmesg, shut down by pressing  off
button for several seconds.

I have reported this bug at  launchpad.net on  2016-11-05.

At that time I used 16.04.1, kernel 4.4.0.  While booting, the screen was
black, one flash, black backlight on-off-on. After more than three minutes,
remote (ssh) access was possible, reboot by SysRQ B.

Recently I tested upstream kernels.
The results depend on the update-state of the installation.

Using installed Version 16.04.2, kernel 4.8.0-36 for installation of the
upstream kernel, booting without workaround parameter:

"boot finished" sound after 45 sec., screen black, no further HDD activity, ssh
login possible, SysRQ reaction.

Using the actual, updated system, kernel 4.8.0-54 for installation of the
upstream kernel, booting without workaround parameter:

no "boot finished" sound, no remote login (ssh).
Reboot/shutdown by SysRQ keys after about 3 minutes possible.