Best answer: Under normal conditions, the Raspberry Pi 4 runs great without any sort of external heatsink and the software throttling keeps everything within safe operating temperatures. However, if you’re using custom software or are overclocking, you probably want to use a set of quality heatsinks.
Heat protection is built in
The Raspberry Pi 4 may be the size of a smartphone, but it couldn’t be more different, and that includes how heat is handled. The Raspberry Pi won’t slow to a crawl when it gets throttled because it was designed for use in the open air or a roomy enclosure.
Thermal throttling is when a computer’s software detects that temperatures have risen above a predetermined safe reading and the CPU is manipulated so that it uses a slower clock speed. This happens on every computer, but you notice it more on some than others. When you’re using a device that’s designed to be thin and inside a sealed case, like a phone or a laptop, the performance hit can be noticeable because the throttling has to happen sooner and be more aggressive.
With the Raspberry Pi, the same software-based throttling is used but you won’t hit the wall as soon and you’ll recover faster because there is more airflow. As long as you’re using things as intended, that is.
If you’re running a custom version of the operating system or an alternative operating system, or you’re pushing things to the limit by overclocking, you might see some performance loss as things aren’t tuned to work together unless you do it yourself. The best way to prevent or minimize this is by using a set of heatsinks. A small investment can make a big difference, and by placing a heatsink over the chips that tend to get the hottest you’ll mitigate much of the throttling performance drop. Luckily there’s one specifically sold for the Raspberry Pi 4.