I recently bought cheap a Onkyo AV Receiver, one of the models with overheating problems...a TX-NR 905.
A brick shithouse thankfully all functional...the graphic chip on the HDMI board is still working.

I have attempted to alleviate some of the excessive heat issues by heatsinking the I.C.s on the graphics board but think some active cooling will be needed.
So...if I go with mounting a fan, do I force cool air in....or suck hot air out.?