MP 6,1 Mac Pro 2013 - DIMM 3,4 Proximity Temperature

[vddobrev]

I am noticing that DIMM 3,4 Proximity temperature is much above DIMM 1,2 Proximity temperature:

DIMM 1,2 Proximity - 43°C stable
DIMM 3,4 Proximity - 57°C to 76°C constantly changing up and down.

Any ideas if this is an indication of an issue and if yes, what may the issue be?

How is DIMM 3,4 Proximity temperature in yours?

 

[m4v3r1ck]

Have you tried Macs Fan Control to view your temperatures sensors. This may give you some more insights.

Good luck.

I've been using MFC tool myself for years to keep my Mac's cool & collective.

 

[vddobrev]

Yes, I am using Macs Fan Control, that is how I noticed the temperatures:

Here on the screenshot DIMM 3,4 Proximity is at 61°C, but it varies constantly, while DIMM 1,2 Proximity is at 41°C and does not fluctuate.

 

[vddobrev]

Isn't there anyone with a MacPro 6,1 that can tell me what is the temperature that you have for DIMM 3,4 Proximity?
I am worried because my MacPro has started to spin the fan to maximum, and the kernel_task is taking all CPU cycles... Please help with how to diagnose what the problem might be.
When my Mac spins the fan to max, there is no other temperature sensor showing a high temperature.

 

[mikas]

Your DIMM temps seem a little strange to me too.

Mine sits at 42-44 °C with moderate load with a D500.
And 35-36 °C with a D300, with newly repasted CPU and GPUs.

Maybe try removing one DIMM from 3 or 4 socket, and/or maybe try swapping DIMMs between the banks.
That's how you would troubleshoot a bad dimm(s) to start with.

Are you using Apple original DIMMs?

btw. those DIMM slots are a little fragile too, one should be carefull with those.

 

[vddobrev]

Your DIMM temps seem a little strange to me too.

Mine sits at 42-44 °C with moderate load with a D500.
And 35-36 °C with a D300, with newly repasted CPU and GPUs.

Maybe try removing one DIMM from 3 or 4 socket, and/or maybe try swapping DIMMs between the banks.
That's how you would troubleshoot a bad dimm(s) to start with.

Are you using Apple original DIMMs?

btw. those DIMM slots are a little fragile too, one should be carefull with those.
View attachment 1962286

Thanks for your reply.

So far I tried:

1. Ran Apple Diagnostics - no issues found.
2. Swapping the 1,2 DIMMs with 3,4 DIMMs - high temperature did not move to DIMM 1,2 but stayed with DIMM 3,4.
3. Removed DIMMs 3,4 all together and only left 1,2 populated - high temperature is still reported on DIMM 3,4.

I am using Apple Original DIMMs that came with the machine.

 

[m4v3r1ck]

Are the GPU the closest to de DIMMs 3,4?

 

[mikas]

Ok, then it's not about the modules.
I did not find the proximity sensors from my pics, at least not yet. I don't even no what to look for though.
Neither does a couple of more fixers in this iFixit Q/A page:
DIMM 3,4 proximity sensor indicating high temperature

 

[mikas]

Took out my spare motherboard. I still can't locate any sensors.
But Dans version on iFixit sounds something worth checking I think.

Those bus bars do locate on DIMM 3,4 side. Connectors and DIMM 3,4 are on the right side of the board looking from the back of the Mac. Blade SSD is on the left side GPU (looking from the back again).

Maybe a slight chance of a dust ball in the wrong place. If so, some compressed air might help, but might need disassembling it too to be sure.

 

[m4v3r1ck]

I would use a ESD - no static vortexes - vacuum iso compressor. A vacuum takes the dust out, a compressor may blow it in some tiny connector or something alike.

But anyway a good inspection and cleanup is always a good - quartile - practice for all computers.

I do hope this will solve your temp issue, good luck.

 

[mikas]

There is PLX pex2723 switch on the right side too. But I doubt it would leak that much temp to the other side of the board. Your PCIe switch diode seems normal, at least comparing to my tCMPs that is (66°C).
PLX is on the upper left in the pic. assembly is upside down, so you have to think about the final location of things.

Of course there is PSU too in there on the back of the board, but that reads 43°C in your pic, so it's not that hot either is it.

edit. totally agree with @m4v3r1ck. Dust is an enemy. And you don't want to let it live in there in your computer. Please look at my D300, beginning the disassembly. It's the DIMM 3,4 area, PSU just behind DIMM sockets.

 

[vddobrev]

Thank you so much to all that replied. I disassembled the Mac and I cleaned everything that I could with 95% alcohol, including the power feed connections. I blow-dust my Mac very often, @mikas it looks nothing like that picture, it had just a few dust particles and some dust balls that came out. While I was at it, I replaced the CMOS battery as well.

I put it back together, and unfortunately the problem remains. As far as I can tell from the MacPro 6,1 diagnostics book that I have, the DIMM 3,4 sensor is located on the CPU Riser card, although it is not certain where it is.

Just to point out - I had the CPU Riser board replaced in an Apple Authorised service centre last September. Unfortunately the warranty for the repair was 90 days only... I am tempted to give it a try and bring it back to them to see if they will make an exception...

 

[m4v3r1ck]

NOTE: smoking in your computer room is also a no-go due to the stickiness of the nicotine residues, keeping the dust on the electronic elements.

Was a smoker myself years ago, so I speak with user experience. Since Mac I went smoking under the kitchen extractor hood.

 

[vddobrev]

NOTE: smoking in your computer room is also a no-go due to the stickiness of the nicotine residues, keeping the dust on the electronic elements.

Was a smoker myself years ago, so I speak with user experience. Since Mac I went smoking under the kitchen extractor hood.

Agreed. But my house is a smoke free environment.

 

[mikas]

Disassembled and assembled allready? You are fast.

Last guess. Maybe it's a broken temp diode or something. Feeding out wrong values, I don't know. You don't have any real problems with your Mac Pro, do you? (I mean maybe appart from the sleep crash bug Apple has given to us).

edit. former smoker too, but on a break, for about 10 years now.

 

[vddobrev]

Disassembled and assembled allready? You are fast.

Last guess. Maybe it's a broken temp diode or something. Feeding out wrong values, I don't know. You don't have any real problems with your Mac Pro, do you? (I mean maybe appart from the sleep crash bug Apple has given to us).

edit. former smoker too, but on a break, for about 10 years now.

I do not have any real problems, other these 2:

1. Crash while sleeping - this is common for all.
2. Fan spins up to maximum and kernel_tasks takes 100% CPU usage - I am attributing this to the problem discussed here namely the DIMM 3,4 higher and fluctuating temperature reading.

So I am also thinking this is a broken or failing temp sensor. I tried to find online the location of it, but I couldn't get an answer... it can be under the plastic DIMM sockets, or on the opposite side of the PCB, or to the side of the DIMM sockets. Without schematics, it is impossible to locate it, but if someone here knows where the sensor is, please do let me know.

As a temporary solution, I set the fan speed to manual and set it to 1200 rpm to keep the temp lower than usual.

 

[vddobrev]

@mikas - I am thinking of examining closely the CPU riser card, but I did assemble my MP already. If you still have your spare motherboard, will you please share some close up pics of front and back with maximum resolution? Perhaps split each side in two pics to show each half. Thanks in advance!

 

[m4v3r1ck]

View attachment mp-2013-late.pdf

I hope this may help you troubleshooting your sensor issue. Cheers

Edit: found the macrumors link on reddit with a search. Love the www.

 

[mikas]

^ That document has been really of great help. I probably wouldn't have dared to proceed with my 6,1 teardown and maintenance without that. But that + iFixit and you're good to go.

My pics from yesterday if needed:
tcMP_cpuboard_full_size_png
I can take some more close-ups today if needed.

 

[vddobrev]

^^ Yes, I have the document, and I have gone through it multiple times. Unfortunately there is no info on the location of the sensor. The document lists that the DIMM sensors are TM0r and TM1r - it also lists in section "Computer Runs Hot" that if any of these sensors fail, the action is to replace the CPU Riser Card.

@mikas - thanks for the full size pics, I will check them out.

 

[vddobrev]

A few days ago I noticed that About this mac is showing only 16GB RAM, and I have 32GB installed. I opened it, removed the RAM sticks and thoroughly blew the connectors with compressed air. I then re-seated the RAM carefully, and now it is all good - 32GB present in the system, and the DIMM 3,4 sensor is back to normal. No more jumping up and down the temperature reading.

 

[vddobrev]

In the end, I had to replace the CPU riser card due to bad temperature sensor.