I have tested now with active cooling and temp about 40 Deg C.
I´m sad, because problems did not chance. Its only with livetv 1080i 50 Hz 25p .
Changed from dvbviewer client to tvheadend client. Problem remains.
As I said, no problems within Kodi or SPMC with android. No problems with 1080p Video file, too.
But I prefer libreelec on all my boxes...
This pic2, I have this specific problem since the first day that all my 3 KIII PRO arrived in my house. But it only happens when I watch DVB-C or DVB-S HD channels. It can be on Android DTV or TVheadEnd. Btw I have a KI pro and it is perfect. That's sad.