http://www.justpushstart.com/2010/06/20/how-hot-can-the-new-xbox-360-slim-gets/
Xbox 360 Falcon – 140 Degrees F / 60 Degrees C Xbox 360 Falcon – 167 Degrees F / 75 Degrees CHow Hot Can the New Xbox 360 Slim Get?
IDLE for an Hour
Xbox 360 Valhalla (Slim) – 123 Degrees F / 50 Degrees CPlaying Modern Warfare 2 for an Hour
Xbox 360 Valhalla (Slim) – 139 Degrees F / 59 Degrees C