I went back to my onkyo 504(75w per channel) after audio died on 805.
I checked the temperature on my onkyo 504. It will max at 38c after listening at -10 for four hours. where as 805 will jump to 69c in no time before internal fan kicks in. Even an external fan didn't help much.
as far as placement is concerned both were kept in same place and both have similar width.
Only diff is its only audio connected to 504. Just an FYI.