From Amazon, I bought this heatsink, with great expectations.
My configuration for 800Mhz operating:
# for more options see http://elinux.org/RPi_config.txt
About 0 o’clock, I put the Raspberry from wooden ground to metal ground, reducing the overall temperature by about 5 °C.
I wanted to reach a maximum temperature of 40-45 °C.
At 19 o’clock, I shutdown the device to install the heatsinks.
As you can see, the temperature is still the same afterwards.
The heat does not have any chance to get out of the case I use, so I took off the top cover.
I’ll upload more pictures as soon as I can find my card reader =)
Taken from http://www.raspberrypi.org/faqs:
What is the usable temperature range?
The Raspberry Pi is built from commercial chips which are qualified to different temperature ranges; the LAN9512 is specified by the manufacturers being qualified from 0°C to 70°C, while the AP is qualified from -40°C to 85°C. You may well find that the board will work outside those temperatures, but we’re not qualifying the board itself to these extremes.