PS4 keeps overheating after cleaning

You may have missed an additional heat source when you opened her up to replace the thermal paste, or maybe the heatsink is not seated firmly on the CPU die. Another possibility is that the fan is on it’s way out, or that the sustained heat from before the repair has destabilized or damaged the CPU.

I would:

1. open it up, check all the thermal grease/thermal pads (like the ones you find on memory chips in computer graphics cards).

2. reseat all of the heatsinks.

3. check to make sure there are no air obstructions in the intake or outtake air ports.

4. check all the power cables to the fans.

5. Check all the soldering points and reflow where necessary with a heat gun or a soldering iron.

Hope this helps.