Chosen Solution
hi, I’ve been having high fan’s rpm for a long time. After installing Macs Fan Control 1.4.11 I’ve realised that the DIMM 3,4 Proximity sensor is showing more than 85º C or more always. Even after a new boot upt. I have 4x16gb RAM modules installed, but even with jus 2x modules in DIMM 1,2 it is still showing DIMM 3,4 proximity temperature really high. What is or where is that sensor? BTW. I tried to reset the SMC, but I’m not sure if I got it (I don’t know how to check if I had success with the reset). The steps I followed where: Turn off Unplug it for 15 seconds Power it again Turn it on after 5 seconds. I’ve opened the Mac Pro and I’ve clean everything , even I replaced the thermal paste. Everything is less noisy, but that sensor has high temperature and I think is responsible for this issue. Is it possible to know what are the threshold values of every sensor that the Mac is using for activating the fans? A friend of mine who own the same machine seems to have higher threshold than mine because I can see lower rpm with much more CPU temperature.
Thanks
OK, This is not going to be easy ;-[ The CPU riser board has a problem. I’m not sure if the sensor its self is the issue or you have a power feed connector failure which is overheating. If you look at these two images you’ll see there is not obvious sensor around the slots (either side). I would have expected there would have been something more visible. What I do see is the power feed stand offs are near the 3 & 4 memory slots. So any corrosion or even a loose connection could cause the connection point to heat up thus the sensor of that side is going off.
Follow this IFIXIT guide to get the fan unit off Mac Pro Late 2013 Logic Board Replacement following through to Step8 then pick up from Step19 and 20 to check the power feed connections to the CPU riser board.
If cleaning the connections & screws using 85% isopropyl alcohol (and you may need a pink pencil eraser if you’ve got corrosion) doesn’t solve the issue, then you’ll need to take the CPU riser board fully out to inspect it. You might even need to replace it.
