I have three DAC PRO+ boards, Two Raspberry 3's, and two of the prior model 2s. I also have two of the steel cases, and one plastic case for the combo. I am running Libreelec (Milhouse nightly), with HDMI out, Ethernet, and one USB IR dongle. WiFi and BT are turned off. With the Raspberry 3 and steel case, my system rapidly gets to 80c, where ARM throttling occurs. You get a little half filled red thermometer in the upper right hand corner, when this occurs. If i play a music video, the system gets to 85c (full red thermometer), and throttles both ARM and GPU. The same setup with Raspberry 2 never gets to 80c. Also, the Raspberry 3 in the plastic case, never gets to 80c. And of course, it all runs fine when no case is used at all. The HDMI usage appears to be the key here. With a headless install (Volumio), I see no heat issues in the steel case.