Thanks for your help to previous posters on this Robert, I'm facing the same issue. Well, not exactly the same.
The system:
Gigabyte B75-D3H
Intel Pentium G620 (Intel HD Graphics)
2GB G.Skill 1333MHz, single slot
Win 7 x64
System is connected to a Marantz SR5005 AV receiver with an HDMI cable. The receiver then connects to a Tohiba AV10 TV using the exact same brand and length HDMI cable. These are Nithos HDMI 1.4 cables.
The problem is that I will get between one and two successful attempts at getting the display working every ten power-ups. Whether they are cold or warm reboots. Whether the TV and AVR are powered up, powered down or in standby.
The biggest problem is that restarting does not fix it - nor does the machine actually restart at all. When I lose all display the board stays powered down, and I can hear the onboard speaker (the little one) clicking away.
I have to carry across a monitor, hook up the cables, and be welcomed by a beep, followed immediately by a 'Failed Boot' screen. After getting into BIOS and then booting all the way into Windows I will still get no display on the TV (monitor works). I then have to run the driver application program to set up all the displays all over again, then unplug the monitor and it seems to work.
My problem is that I never know if I will have a picture on my screen when I turn the machine on. I've had EDID problems with Intel graphics before (when 1680x1050 wasn't a supported resolution back in '04) and I suspect it's something similar.
On a side note, I get a lot of these 'Failed Boot' screens (from the first day I've used this motherboard and CPU), even when the PC was connected to only a monitor. I am not sure if the problems are related to each other, or because of a faulty component.
Obviously this has gone to a whole new level - once I hook up the AVR and TV and expect it to work exactly the same way as a monitor, and it doesn't.
I do know your level of support for third-party products isn't really at the same level as your own motherboards, but I hope that you may be able to offer some insight. I was really hoping that my first Intel system in 8 years would give me a good video experience. It's not there yet - I can take any competing chipset motherboard, plug and unplug all sort of displays, start it headless and plug in a display later, or remove a display before restarting and still be able to get some sort of picture on a screen. The way it is now, the graphics card (in the CPU) is blind and keeps the motherboard in suspend until it detects what it deems to be a valid display on its output.
Strangely enough, the system does start when it is fully headless (no video connections at all, into any port), it simply refuses to do so when it feels like it (apparently, as I cannot find any reproducible symptoms).