First- I'm a PC (Windows) guy (family breadwinner, not a fanboy), embedded systems hardware and firmware developer, software developer- running Linux server (non-expert) for about 15 years.
I have a friend who I setup with a Pi-b rev. 3 (with Berryboot, OpenElec, Wheezy). In each of those three GUI's the screen intermittently goes blank. He has a Westinghouse TV (VK42F240S) TV. It's supposed to be (according to the User Manual) 1080p, 60Hz (other profiles are supported). However, left to itself, the Pi blanks the screen approx. every second for about a second each time. (This happens when Berryboot, Wheezy, or OpenElec are running). The Video Status shows that we're running at 1080p, 60Hz in OpenElec. BUT- when I start a video via add-in, or file playback- it is FINE.
I have tried modding the config.txt file in BerryBoot. I have tried the video settings in OpenElec (everything available). But the problem persists.
When I change BerryBoot's config.txt, to, for example, ignore EDID (hdmi_ignore_edid=0xa5000080
), and try to set the display to say 1080p, 50Hz (my video experience says that this is a refresh rate problem)- with the caveat that I am often wrong before I am right with a recent problem- the screen goes into a "vertical letterbox" mode with borders on the right and left, but video top-to-bottom.
So the documented video modes (hdmi_group, hdmi_mode) seem to have unexpected effects. Setting to "Cheap Chinese monitor (ignore)" and some supposedly supported mode, results (usually)
in usually a narrow screen, and sometimes a completely blank screen.