4k resolution - Intel NUC overheating (hot), video stuttering

I have an Intel NUC 7^* (NUC7i5BNH). Approx 1 year old.

Running watch sensors on Linux shows an operating temperature of 95 °C.
Windows shows 99 °C.

Many stalling issues, including: cannot play 4k video in YouTube, but 4k videos in VLC work fine.

After opening the NUC, inside the case looks perfectly clean – zero sign of dust.

Why is it overheating?
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^* Unlocked | (Newegg.com) says:

…  NUC is Intel’s designation for their ultra-small self-contained personal computers.  The acronym NUC stands for Next Unit of Computing, which perhaps purveys the idea that in the near future, home computers could become this small as a matter of standard. …

Answer

There is a non-obvious trap with the Intel NUC's, upon inspection the internals can look perfectly clean and dust-free...

However, there is a spot between the cooling fan and the cooling fins, where dust gets trapped and causes overheating. Unusually, this is not possible to see upon a normal inspection, even if you remove the motherboard from the chassis.

Solution:

1. Open the NUC, via the 4 screws at the bottom.


2. Remove ram/ssd, and all plugged wires - take a photo first so you know where to plug the wires back in later.


3. Carefully remove the mother board from the chassis - There are two screws holding the motherboard in on the NUC7.


4. On the back side of the motherboard, you will find the cooling fan and cooling fins/air intake. (these may look perfectly clean)


5. Unscrew the two screws holding the fan in, and remove the fan.


6. You may find a big clump of dust inside - blow out the cooling fins and the fan with a can of compressed air - (perhaps available at your local dollar store).

Credit to Stokanator: https://communities.intel.com/message/570261#570261