HDMI TV turns on shortly, then goes black, turns on shortly, goes black and so on

My new TV device is here with only HDMI inputs. But when connecting my Mythbuntu 12.04 box, the screen turns on for a second only. Then it is black for a while, then it displays "no signal" and after about a minute it turns on for a second again! (and so on) This even seem to be persistent behavior when rebooting the mythbuntu system!

But I found a hack: connect the DVI output of the mythbuntu system to my old TV device - works - disconnect it - connect the new TV via HDMI to DVI adapter to the DVI output the old TV device was connected before - voilà, the new TV turns on and shows the mythbuntu screen persistently!

The downside (besides the fact that I don't want to do this every time): the resolution is still the lower native resolution of the old tv and not the higher native resolution of the new tv.

When adjusting the resolution at this stage, everything starts from the beginning again. Connecting the old tv device via HDMI works without a problem, though. Therefore I am unable to blame a device, interface or protocol...

Nevertheless it seems that the new tv device has some protocol issues with the mythbuntu box and when connecting it via dvi to the old tv prior, the mythbuntu system seems to simply proceed with outputting the video signal - which can be connected to the new tv device then.

The xrandr output supports this theory:

htpc@htpc7even:~$ xrandr
Screen 0: minimum 320 x 200, current 1360 x 768, maximum 8192 x 8192
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 connected 1360x768+0+0 (normal left inverted right x axis y axis) 1280mm x 720mm
   1920x1080      60.0 +   50.0     24.0  
   1600x1200      60.0  
   1680x1050      60.0  
   1400x1050      60.0  
   1280x1024      60.0  
   1440x900       59.9  
   1280x960       60.0  
   1280x800       59.8  
   1024x768       60.0  
   800x600        60.3  
   640x480        60.0  
HDMI2 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
  1360x768 (0x46)   85.5MHz
        h: width  1360 start 1424 end 1536 total 1792 skew    0 clock   47.7KHz
        v: height  768 start  771 end  776 total  795           clock   60.0Hz
htpc@htpc7even:~$

The new tv device supports up to 1920x1080

The old tv device supports up to 1360x768

The latter is the exact resolution for the signal informations at the bottom of the xrandr output which is not assigned to any of the output devices; so even xrandr seems to not know where this signal is send to.

Assuming, this is a complex issue, I request a two-step answer:

Workaround: is it possible to get the above described state without connecting the old tv device (or any other device) prior?

Final solution: well, how can I solve my issue?

Thanks in advance!

Mythbuntu system data:

Mainboard: Asus P7H55D-M EVO
Graphics: using onboard Clarkdale graphics!
System: Ubuntu 12.04.5 LTS
uname: 3.2.0-68-generic #102-Ubuntu SMP Tue Aug 12 22:02:15 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
Desktop environment: standard Mythbuntu XFCE

Update

I booted my htpc machine with Ubuntu 14.04.1 via usb and this live environment was able to turn on my new tv persistently without a problem.

Because I wondered if XFCE may be the problem, I installed Gnome on the mythbuntu system, but this failed the same way as XFCE.

Additionally, I noticed that when booted up the mythbuntu system with both tvs connected (the old one via DVI and the new one via HDMI), the XFCE display settings dialog got confused and swapped the supported resolutions lists so that I am unable to adjust correct resolutions. For the old tv the name was assigned wrongly as well and the other name did not appeared and the entry was named "HDMI1" only. Previously I saw all kinds of informations there: HDMI1, HDMI2, name of the new tv, name of the old tv. Even xrandr listed the wrong resolutions per HDMI output.

Now I am not sure if this behavior was/is reproducible as I am logged into Gnome currently which listed the supported resolutions correctly and named the tv devices correctly.

After a full system backup I make a release upgrade just now to see if Ubuntu 14.04.1 solves the issue as the live system did.