Cooling The Raspberry Pi 4 With The Fan SHIM & FLIRC For Better Performance
With the multi-threaded John The Ripper we see the significantly lower performance out of the Raspberry Pi 4 without a heatsink or even using a basic heatsink but the Fan SHIM and FLIRC allowed the Pi4 to hit its optimal speeds.
John The Ripper caused the Cortex-A72 cores on the BCM2835 to run at 83 degrees but with the Fan SHIM that was 52 degrees on average or just 44 degrees with the FLIRC case. (The additional runs for some of the benchmarks is due to high variation between the multiple runs in the case of thermal throttling, which the Phoronix Test Suite then by default dynamically increases the run count in order to try to lower the deviation to yield a more accurate result.)
The libjpeg-turbo benchmark workload wasn't intense enough to cause any throttling, but the temperature difference is very clear.
In demanding workloads like x264, the performance difference from inadequate Raspberry Pi 4 cooling is very clear.