Results from the first set of tests:

Results from the second set of tests – comparisons of scenarios with the original firmware and the new firmware:

Additional results:

• The official Raspberry Pi case and the Flirc case exhibited an elevated temperature at the end of testing (after 25 minutes of idle operation following the stress test). Additional testing was performed for another 30-60 minutes to determine whether the cases would continue to cool. In both cases, additional idle time did not yield further cooling – the cases remained at an elevated temperature.
• Measurement of case temperatures yielded the following results:
  • All of the active-cooling cases remained near room temperature at all times, including peak load.
  • The enclosed (fanless) case exhibited a case temperature of 43.2°C while the CPU was operating around 80°C.
  • The official Raspberry Pi case exhibited a case temperature of 40.1°C while the CPU was operating at 66°C, and 47.4°C while the case was operating at 87°C.
  • The Flirc case exhibited a case temperature of 45.4°C at max CPU temperature under load. The sides of the case were significantly warmer than the top of the case, which has a rubber-like coating. (The heatsink block that is integrated with the the Flirc connects to the top of the case. The rubber probably insulates the top where the temperature is the highest, and the case primarily radiates heat through the sides.) The case also remained warm longer than the other fanless cases.
• The fans in the active-cooling cases run 100% of the time – even while the RPi is shut down – because they are connected to the 5V supply, which passes current at all times. The sound level of each fan were measured as follows:
  • Generic 5V fan: 60 dB up close; 48 dB one foot away
  • Noctua 5V fan: 50 dB up close; 42 dB one foot away

The raw data is available in this Excel spreadsheet. (Yes, I’m aware that Excel certainly isn’t the best way to keep and analyze data. This is a free-time project, so I used the easiest tool on hand.) The first tab (“Tests”) is the raw output from each trial; the second tab (“Analysis”) is the data extracted from the raw output; the following tabs are charts; and the last tab (“Info”) is just some version info about the Raspberry Pi used for the testing.