Chrome Version: 58.0.3029.51
Chrome OS Version: 9334.33.0
Chrome OS Platform: Lenovo N22 (Reks Touch)

Steps To Reproduce:
1.Connect external display, keyboard, mouse
2.Close the lid on Chromebook  
3.Wait for ~30 min up to a few hours and display becomes completely black.   

Expected Result:
External monitor work all the time 


How frequently does this problem reproduce?:
Allways (but takes different amount of time to repro)

There is no workaround at this moment and customer have to reboot a device. 


I was able to reproduce the issue, external screen got completely blank in about a hour. 
As I can see from the logs it seems to be related to crbug/677332 but raising a new one to verify: 

2017-04-11T11:21:11.373330-07:00 DEBUG kernel: [ 1082.060527] SELinux: initialized (dev proc, type proc), uses genfs_contexts
2017-04-11T11:21:12.657522-07:00 ERR kernel: [ 1083.344309] [drm:intel_cpu_fifo_underrun_irq_handler] *ERROR* CPU pipe C FIFO underrun
2017-04-11T11:29:42.532320-07:00 DEBUG kernel: [ 1593.202339] SELinux: initialized (dev proc, type proc), uses genfs_contexts
2017-04-11T11:29:51.239341-07:00 DEBUG kernel: [ 1601.909023] SELinux: initialized (dev proc, type proc), uses genfs_contexts
2017-04-11T11:33:18.081346-07:00 DEBUG kernel: [ 1808.744970] SELinux: initialized (dev proc, type proc), uses genfs_contexts
2017-04-11T11:47:04.351519-07:00 INFO kernel: [ 2634.987562] cros-ec-dev cros-ec-dev.0: Some logs may have been dropped...
2017-04-11T11:48:18.225313-07:00 DEBUG kernel: [ 2708.859621] SELinux: initialized (dev proc, type proc), uses genfs_contexts
2017-04-11T11:55:16.864128-07:00 ERR kernel: [ 3127.484864] [drm:intel_cpu_fifo_underrun_irq_handler] *ERROR* CPU pipe C FIFO underrun
2017-04-11T11:57:30.630331-07:00 DEBUG kernel: [ 3261.246275] SELinux: initialized (dev proc, type proc), uses genfs_contexts

Full log: https://drive.google.com/open?id=0By9xEkAUmm_cYncwYW9iTllSeUE
Video of the issue: https://drive.google.com/open?id=0By9xEkAUmm_cUGZiWmlfTVpRMTg
about:gpu: https://drive.google.com/a/google.com/file/d/0By9xEkAUmm_cUGVwZkVWcXZxcHM/view?usp=sharing