Hey.
The performance settings in BIOS seems to default so that in "normal" state you get a quiet NUC and in "turbo" state you get to hear the ventilation a little more with the increased performance while still keeping a temperature belove < 70 degrees, and Intel don't recommend changing any of this. Intel Tuning Plan is probably meant for rigs with extra cooling applied, and the NUC casing doesn't leave room for that kind of cooling.
The BIOS setting Sustained Mode Time just seems odd, because if the turbo mode is supposed to start as the workload increase, why should it stop because of a time limit instead of lesser CPU use??
