Here’s the latest picture of Charlene’s Pi-4:
Do you see the difference?
Wait for it. . . .
Ahh! There it is! Down in the lower left corner. . .
. . .the small heatsink on the power management chip.
Here’s a heat map of the Pi-4, taken in late 2019:
Though the CPU gets all the good press, (and heatsinks), the power management chip, (lower left), also gets significantly hot, but has been ignored by the heatsink manufacturers up until the advent of the Pi-5.[1]
Here’s the chip prior to having a heatsink glued to it.
As you can see, I took a different heat sink and cut it into small pieces and glued one if them to the chip with thermally conductive adhesive.
Adding the heatsink to the PMU chip can help reduce its heat load and, (indirectly), the heat load of the entire board/robot.
What say ye?
==================== Footnotes ====================
- Since the advent of the Pi-5, (or slightly before), some of the modern monolithic Pi-4 heatsinks also include a nub and thermal pad for this chip.