I've been having better luck watching BR rips on an ATV 3 since i tuned its profile down to limit the bitrate to about 25mbit. Sadly my copy of Winter Soldier yearns to average 33+ mbit, and the poor little ATV3 just can't seem to keep up. By which I mean crashes HARD and reboots. It seems like more recent movies are really pushing the capacity of this little hocky puck, and Apple even claims a max bitrate of 25.
Before I start to build a custom Plex client box, has anyone ever tried pushing the ATV3 past its limits using more aggressive cooling?