Originally Posted by maxruss
I did not use any fans, but the unit was on open stage. The room is air-conditioned with permanent temperature and humidity. First sign of future failure was after I returned from summer vacations and plugged it in.
It does seem that the units that have had early failure have been those that have not had external cooling from the start, or from very early in the unit's life.
Even those units that have been on an open shelf, with plenty of clearance all round, like your own, seem to suffer HDMI board failure.
It is clear from your experience with the service centre that Onkyo know they have serious problems with the HDMI board in the .x07 series - so much so they seem to have run out of replacement boards! In the USA they are sending people brand new x09 series units as replacements because they can't repair or replace the HDMI boards fast enough.
I'd repeat my advice to everyone with a x07 unit that has not so far had problems with HDMI dropouts etc: get two 4 inch PC fans and place them on the rear half of your unit.
I guess the other side of that is to deliberately not use fans, if the unit is still in warranty, and try to provoke HDMI board failure so that Onkyo can deal with it under warranty. Unfortunately, if your case is typical, that may result in being without a unit at all for months on end, which is, of course, not at all satisfactory.
I imagine that Onkyo have learned a lesson from this and that the x09 series have HDMI boards that are up to the task demanded of them.