Screen sleep resulting in black screen of death (ubuntu 16.04 / intel i7 4790k / ga-z97x-ud3h-bk )
Possible fixes are:
1) restart X and loose current session
2) replace SNA with UXA and be happy foverer (best solution)

How to detect bug:
cat /var/log/Xorg.0.log | grep sna_mode_shutdown_crtc
(EE) intel(0): sna_mode_shutdown_crtc: invalid state found on pipe 0, disabling CRTC:21

How to fix:
Copy and save script above, and do:
sudo sh