check to see how much solid contact the apu is making with the heatsink. that seems to be a huge problem for a lot of people, they just dont know it. it was my problem on my 2 pro. to test it you need to use as5 as mx4 is too clumpy whereas as5 applies like a grease kind of. put a thin layer of as5 on the apu and spread it out with an old credit card or use the plastic spreader that comes with the mx4. then clamp everything dn, put all screws back in, basically put it back together except for the wires and top/bottom exterior shells. then pull it apart again and observe the apu. if you have a tiny spot on the chip where there is little to no thermal paste and the rest of the chip is covered in it then that little spot is the part of the chip that is making solid contact with the heatsink, good solid pressure. this is why there is hardly any thermal paste there in that tiny spot because the good solid pressure is squeezing it out. and that is why its running hot because the chip cant keep cool if only 10% is making contact with the heatsink. sounds crazy but its a huge problem for sony as the apu's are not exactly flat. i had to lap my heatsink with 1000 grit sandpaper to make it fit the contour of the apu. i have attached some before and after pics. i had about 10% solid contact before and now have about 50% solid contact and my fan finally shut up and i had a 4 degree across the board drop in temps testing with orbis across multiple games. ambient room temp has a lot to do with it too as at about 75 degrees room temp my fan finally starts to kick in ever so slightly when playing gow 2018. check your apu first and if its ok then try some gelid ultimate pads. you can also look at the heatsink in addition to lookin at the apu to see if you have any bare spots which indicate solid contact. i did a bunch of hardware mods on my trying to figure it out and the last thing i did was lap the heatsink and that is what did the trick. i wish i would have done that first. it would have saved me about 100 hours of work and 200 bucks in supplies. you can see in the first pic on the left side of the chip there is a small spot on the heatsink with no thermal paste--this is the spot that is making solid contact with the apu and on the second pic after lapping the heatsink with 1000 grit sand paper almost the entire left side of the heatsink is now making solid contact with the apu, this resulted in a 4degree drop across the board and a quiet fan.
