Remy at Spanish-language tech site Geektopia is a Raspberry Pi enthusiast with access to a thermal imager. Sounds like my kind of guy. He writes (per mine and Google’s hack Spanish):
After a long wait since its release, I recently came into possession of a Raspberry Pi computer, and the first thing that struck was not how easy it is to use or the incredible community that’s built up around it in such a short time: I was surprised at how hot it gets. Since I have access to a Fluke Ti35 thermal camera, I set out to do a little study of this miniature computer in operation.
Remy identifies three integrated circuits on the RasPi PCB that generate most of the heat: the processor (Broadcom BCM2835), the ethernet controller (SMSC LAN9512), and the voltage controller. Click through, below, to read about his conclusions and methods and to see the heat maps of his Raspberry Pi at rest, while playing video, while transferring files over the network connection, and while running a special “stress test” program that Remy wrote himself.
Thanks to Jacob Marsh at UK’s ModMyPi for assistance with this post. If you’re concerned about your Raspberry Pi’s heat dissipation, they’ve got a 3-pack of ready-made RasPi heat sinks available for just five quid.