RP4 overheating in OEM case

I had it in mind that should a PI ever come with Gigabit Ethernet and USB3 support, i would set one up as one of my work-stations. When the PI4 came out I was overjoyed to hear that it had both these features and a lot more. So I popped online and ordered one of the standard kits with PI, case, SD and power supply, and of course the micro-hdmi cable. After delivery when I unpacked it, I couldn’t help but feel that this tiny board couldn’t possibly deliver on its promises without some sort of cooling. So after installing it it inside the official PI4 case which btw has no active or even passive cooling, i did some thermal testing. I wasn’t overly surprised when it ran at 79 degrees Celsius with minimal load e.g browsing blogs etc. Running the sysbench utility with 4 threads pushed the PI into thermal throttling within a few seconds. That greatly reduces its performance so I popped online again and ordered the passive cooling case above from Aliexpress to see if it would solve the overheating issue. This case came in two varieties, one with fan and one without. I went for the fan-less option. I love having a silent working environment and am also not a great fan of moving parts where they can be avoided. After delivery and installation, i ran a few tests to see if the new case could dissipate enough heat under ambient room temperature of 21 Degrees Celsius. Below are some stats showing the thermal behavior with the new case installed and each CPU core maxed out to 100%.

Some tests

Full test period (~4.65h)

Test period capped at end of load-test (2.3h)

It seemed to do its job just fine. Out of curiosity, i set the PI up vertically with the cooling ribbs pointing up and down (Ethernet and USB pointing up). Below graph shows the graph above split into before the switch and after.

Test period capped at switch to vertical alignment (1.23h)

Test period starting at point of switch to vertical alignment (1h)

Conclusion

Putting the Pi upright did seem to slightly improve heat-dissipation but not by much. Overall the case performed well for being a passive cooler. With it in place the RP4 could utilize all its CPU cores while staying far away from critical temperatures. Note however that the GPU has not been tested in conjunction with the CPU so the temperature in such a case could approach the throttling limit. I might do another test for that.