Poor man's heatsink setup - from 48°C to 35°C (118°F to 95°F)

[MarkHaysHarris777]

Back to the heat sink: I thought wrong that the paste would hold the heat sink in place.
This seems to be not the case.
How do you fix the heat sink on the pine pcb ?

The correct procedure is to use 3M thermal tape. The 3M tape (designed by 3M for the purpose) does dual duty... it is a thermal conductor, as well it is an adhesive. You can purchase the tape on-line. You place the tape on the heatsink (overlap just a bit) and then you place the heatsink on the chip (get it where you want it once, they tapes are hard to remove)