A Resolve Diagnostic Log would be helpful:
viewtopic.php?f=32&t=71894If ForceWare 388.13 is the NVIDIA driver version, try the current 391.35 version of the driver.
If you have the scopes displayed, select Info instead.
Also try setting Project Settings - Master Settings - Video Monitoring - Video Bit Depth to 8 bit to see if that makes any difference.