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MP 1,1-5,1 Mac Pro 4,1 high fan speed, Heatsink temp sensor issue?

B

btjtaylor

macrumors newbie
Original poster
Nov 23, 2016
11
3
Hi all

I have a Mac Pro 4,1 flashed to 5,1 with 2x X5680s installed

I have an intermittent problem where some of the fan speeds in machine will go to 100%, even at idle, which is incredibly noisy,

I believe I have diagnosed the issue as being with the heatsink temp sensor for CPU A, in the below screenshot you can see that some of the fans are running at 100%, and the HeatSink temp sensor is not reading a value.

Screenshot 2019-12-01 at 00.36.01.png


If I use a third party tool like "Macs Fan Control" I can work around the issue but i'd really love to have a proper solution,

My question is, is this part replaceable? Is there a connector for it somewhere?

Thanks in advance
Ben
 
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btjtaylor said:
Hi all

I have a Mac Pro 4,1 flashed to 5,1 with 2x X5680s installed

I have an intermittent problem where some of the fan speeds in machine will go to 100%, even at idle, which is incredibly noisy,

I believe I have diagnosed the issue as being with the heatsink temp sensor for CPU A, in the below screenshot you can see that some of the fans are running at 100%, and the HeatSink temp sensor is not reading a value.

View attachment 888867

If I use a third party tool like "Macs Fan Control" I can work around the issue but i'd really love to have a proper solution,

My question is, is this part replaceable? Is there a connector for it somewhere?

Thanks in advance
Ben
Click to expand...
The sensor is that black component with the transistor format glued/screwed to the heatsink. The sensor signal goes to the same connector as the fan. See the photo:
dual 2009 Mac Pro - heatsink temp sensor.jpeg


If you have another dual CPU tray, maybe you can change the heatsinks from one to the other and check if it's a problem with the tray or the heatsink sensor itself.

In the past I changed the fan/sensor/connector from heatsink a to B to check if the problem was the tray or the sensor, unfortunately after all the work it was the tray.

Btw, if you are using lidded Xeons with a 2009 tray, you can easily have bad contact between the tray and the heatsink connector.
 
Thanks for that, i dont have another tray im afraid but i iwll check that component to see if it looks damaged in any way, maybe the connector on the right side is loose also,

By the way does anyone know which socket in the tray is A and which is B? I cant see any labelling on the board
 
The unnecessary intermittent max fan speeds of your CPU heatsink coolers indicates you probably have a damaged CPU Tray , a poor CPU Heatsink fan cable connection to the Tray's PCB or as Alex tsialex pointed out a failing thermal sensor . CPU A is in the rear of the Mac .

What happens to your CPU Heatsink fan speeds when you push both processors at full load ? I've built these DP Systems with those fan speeds not needing to go beyond 1700 RPM continuous when everything is cooled and assembled properly . The use of MFC at the proper settings for these 12 Core 3.33 or 3.46 GHz Builds is mandatory for durability .
 
Last edited:
Thanks for the feedback all. I'm using "lidded" CPUs which could be part of the problem, I know it's not ideal but I didnt want to delid as it seems very risky on these chips,

I took the CPU/RAM tray out and noticed the hex screws for the CPU A cooler were very loose - I remember when I did the upgrade I was worried about breaking something by overtightening, maybe too worried! I took the CPU A heatsink off and cleaned out the plug and the connector on the board with a little contact cleaner. I reinstalled the heatsink and tightened up the screws ever so slightly more than they were before.

I've booted the machine back up and for the moment it seems ok, i've rebooted a few times and no issues with the heatsink temp detection so far ... fingers crossed!

If im still having issues I think delidding the CPUs is the next step so they fit more like the OEM ones should
 
tsialex said:
The sensor is that black component with the transistor format glued/screwed to the heatsink. The sensor signal goes to the same connector as the fan. See the photo:
View attachment 888883

If you have another dual CPU tray, maybe you can change the heatsinks from one to the other and check if it's a problem with the tray or the heatsink sensor itself.

In the past I changed the fan/sensor/connector from heatsink a to B to check if the problem was the tray or the sensor, unfortunately after all the work it was the tray.

Btw, if you are using lidded Xeons with a 2009 tray, you can easily have bad contact between the tray and the heatsink connector.
Click to expand...
How can you exchange heat sensor A to B?
 
Trungha said:
Is it dangerous? There will be a problem with the screws at the fan! Can you get them back to where they were before! Thank you!
Click to expand...
It's an easy operation for someone with experience, but a person without the skills can destroy the heatsink. It's better to get another heatsink to test than try to do it.
 
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tsialex said:
It's an easy operation for someone with experience, but a person without the skills can destroy the heatsink. It's better to get another heatsink to test than try to do it.
Click to expand...
Thank you! Are these snails at risk? See the picture below!
 

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Trungha said:
Thank you! Are these snails at risk? See the picture below!
Click to expand...

Btw, if you are asking if it's safe, it's not an operation for your level of expertise. After the test, you will need to glue the cables again and reinstall the fan - it's easy to damage the fan rubber supports.

Usually the problem is on the tray itself and not with the sensor.
 
tsialex said:
Btw, if you are asking if it's safe, it's not an operation for your level of expertise. After the test, you will need to glue the cables again and reinstall the fan - it's easy to damage the fan rubber supports.

Usually the problem is on the tray itself and not with the sensor.
Click to expand...
Thank you for the help! My english is really not good! I understood the problem
 
Another example for why to delid Xeons for Dual 4.1

It's all doable but a pita, imho much more fiddling than the additional step to get the heat spreader off and build a cpu board the way it was designed to.
 
btjtaylor said:
Hi all

I have a Mac Pro 4,1 flashed to 5,1 with 2x X5680s installed

I have an intermittent problem where some of the fan speeds in machine will go to 100%, even at idle, which is incredibly noisy,

I believe I have diagnosed the issue as being with the heatsink temp sensor for CPU A, in the below screenshot you can see that some of the fans are running at 100%, and the HeatSink temp sensor is not reading a value.

View attachment 888867

If I use a third party tool like "Macs Fan Control" I can work around the issue but i'd really love to have a proper solution,

My question is, is this part replaceable? Is there a connector for it somewhere?

Thanks in advance
Ben
Click to expand...
Did you solve the problem?
 
Yes after using contact cleaner on the connector underneath the heatsink and making sure it was all tightened down properly I didnt have any more issues
 
Could it be because with lidded CPUs , there's more distance between the fan/sensor plug and the header on the pcb?
Since the plug is fixed in the heatsink, the thickness of the lid will result in more distance to the header.
Sometime ago, I've seen a video where the guy showed how to detach the plug from the heatsink, and be able to plug it in completely...
 
KeesMacPro said:
Could it be because with lidded CPUs , there's more distance between the fan/sensor plug and the header on the pcb?
Since the plug is fixed in the heatsink, the thickness of the lid will result in more distance to the header.
Sometime ago, I've seen a video where the guy showed how to detach the plug from the heatsink, and be able to plug it in completely...
Click to expand...


only if you install the wrong CPU.
so lidded in the 4.1 dual and then the distance is no longer correct,
or insert the plastic spacer incorrectly on a de-lidded.

if you do everything right, the plug is identical with the one from the 5.1
 
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btjtaylor said:
Hi all

I have a Mac Pro 4,1 flashed to 5,1 with 2x X5680s installed

I have an intermittent problem where some of the fan speeds in machine will go to 100%, even at idle, which is incredibly noisy,

I believe I have diagnosed the issue as being with the heatsink temp sensor for CPU A, in the below screenshot you can see that some of the fans are running at 100%, and the HeatSink temp sensor is not reading a value.

View attachment 888867

If I use a third party tool like "Macs Fan Control" I can work around the issue but i'd really love to have a proper solution,

My question is, is this part replaceable? Is there a connector for it somewhere?

Thanks in advance
Ben
Click to expand...
sorry guys for the time travel. My baby, my 5,1 has started running with fans at full speed from boot, AHT say an SMC issue. SMC flasher doesn't fix it. the image above shows running temps across the logic board, but no where does it say what the app is. I have no idea if it's a wire, or a sensor... can someone let me know what the app is/was so I can probe the temps and see if I can fix it..? thank you..
 
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