Short update: After a few more hours of number crunching, I realized a small drop in performance.
With Intel’s Monitoring Tool, I saw that the CPU is running stable at 87° C, but the motherboard starts throttling.
The Technical Product specification for the NUC Board states:
“A chassis with a maximum internal ambient temperature of 50°C at the processor fan inlet is recommended. If the internal ambient temperature exceeds 50°C, further thermal testing is required to ensure components do not exceed their maximum case temperature.”
As there is no setting in BIOS to adjust internal ambient sensor threshold, I played with maximum CPU Speed to solve this.
Using 2-Core Turbo Ratio of 24 results in a maximum speed of 2.4Ghz. With that settings the temperatures look much better:
Package TPD: 17 Watts / Temperature: ~77° C / Outside Case Temp: ~52°C
Also, there was no motherboard throttling in the last 24h
Conclusion: Intel’s default thermal solution is doing a great job