Resolved The 5,1 Fan Conondrum

[theStruggle]

Hello, my first post on this forum and sadly it isn't a nice one; but it could end up nicely - I hope!


I've had a problem with my precious 5,1 for a long time. Then I became ill and didn't try to fix it - instead resorted to my PC, which annoys me every day no matter the great performance. I'm getting better now and doing another attempt to at least figure out what happened, and perhaps get it fixed in the process.


What seems to be the problem?

Both of the bottom fans (which cools down the processor heat block)
on my Mid 2012 MP 5,1 stopped working. There are no apparent red lights
on the motherboard.


What methods did you try to find the source of the problem?

1. Tried connecting the 5,1 fans to my PC to see if they would work.
   They do not.
   
   
2. I connected a pair of aftermarket fans to the 5,1 case. They do
   not run. However they run on my PC.
   
   
3. I made an USB stick with the ASD 3S149, and ran the tests. The
   fan test immediately fails after the first one completes
   (The fan in front of the graphics card).
   
   
4. Removed all the RAM sticks an left only one to see if any of them
   could possibly be a source to the problem.
   
   
5. PRAM/NVRAM & SMC Reset

Solution
The fan connectors were mounted upside-down, which was a stupid mistake. However the plastic mounts on the pins were removed so I thought it was a non issue and mounted the connectors whatever way I felt like, upside-down that is.

Thank you very much for helping me remember!
_______________________________________________

I'm not sure what to do anymore, guys.
Thank you for reading and possibly answering!

 

[tsialex]

Hello, my first post on this forum and sadly it isn't a nice one; but it could end up nicely - I hope!


I've had a problem with my precious 5,1 for a long time. Then I became ill and didn't try to fix it - instead resorted to my PC, which annoys me every day no matter the great performance. I'm getting better now and doing another attempt to at least figure out what happened, and perhaps get it fixed in the process.


What seems to be the problem?

Both of the bottom fans (which cools down the processor heat block)
on my Mid 2012 MP 5,1 stopped working. There are no apparent red lights
on the motherboard.


What methods did you try to find the source of the problem?

1. Tried connecting the 5,1 fans to my PC to see if they would work.
   They do not.
   
   
2. I connected a pair of aftermarket fans to the 5,1 case. They do
   not run. However they run on my PC.
   
   
3. I made an USB stick with the ASD 3S149, and ran the tests. The
   fan test immediately fails after the first one completes
   (The fan in front of the graphics card).
   
   
4. Removed all the RAM sticks an left only one to see if any of them
   could possibly be a source to the problem.
   
   
5. PRAM/NVRAM & SMC Reset

Q: Related to the ASD 3S149 TEST:

If the sensor test goes through with flying colors; does that per automatic
mean that there is no error in the Logic board? If that is the case, why
doesn't any of the fans connected to the bottom work?


_______________________________________________

I'm not sure what to do anymore, guys.
Thank you for reading and possibly answering!

You can't test a Mac Pro fan with a PC, Apple used a very different way to control rotation. There is a old post here somewhere that explains in detail exactly what Apple did, I don't remember exactly what is.

You should try to test with another Mac Pro to check if it's the fan itself or a problem with the backplane fan connector or backplane SMC.

 

[theStruggle]

You should try to test with another Mac Pro to check if it's the fan itself or a problem with the backplane fan connector or backplane SMC.

First of all, thank you very much for responding!

However I can put a normal PC fan into the Mac Pro? I tried it before my Mac fans stopped working and the ”normal” fans went on full speed. Now when I’m trying however they don’t spin at all. I have no way of testing my original fans with another Mac Pro, sadly. There is nothing else I can do?

 

[tsialex]

First of all, thank you very much for responding!

However I can put a normal PC fan into the Mac Pro? I tried it before my Mac fans stopped working and the ”normal” fans went on full speed. Now when I’m trying however they don’t spin at all. I have no way of testing my original fans with another Mac Pro, sadly. There is nothing else I can do?

If I remember correctly, you have to do a circuit to convert PC PWM fans rotation signals to the way Mac Pro SMC expects the fan signal.

If I had this problem, I'd buy at least one of the fans from someone that is parting a Mac Pro. It's the same Delta part number from 2008 to 2012.

 

[theStruggle]

If I remember correctly, you have to do a circuit to convert PC PWM fans rotation signals to the way Mac Pro SMC expects the fan signal.

If I had this problem, I'd buy at least one of the fans from someone that is parting a Mac Pro. It's the same Delta part number from 2008 to 2012.

Ok, I’ll do that! Thank you!

I’m also curious about how fussy the motherboard is about the original fans in general. Let’s say I have both fans in working order: but switched places with the front and exhaust fans...would they run at all?

Another question: is there a way to find out what the correct identification number for the front fan and the exhaust fan?

 

[tsialex]

Ok, I’ll do that! Thank you!

I’m also curious about how fussy the motherboard is about the original fans in general. Let’s say I have both fans in working order: but switched places with the front and exhaust fans...would they run at all?

Another question: is there a way to find out what the correct identification number for the front fan and the exhaust fan?

Fan is the same for both places, it' just the assembly that is different. If you remove the assembly from the CPU tray cage, you will see the label.

This is the front fan assembly:

 

[crjackson2134]

Nice! I didn’t realize they were brushless.

 

[theStruggle]

Fan is the same for both places, it' just the assembly that is different.

That's great! Thanks for that.

Let me show you what the motherboard looks like with the focus on the front and rear pins. Sadly I don't have a close up on the rear, but they look more or less the same. Is there anything that could be said about that? Please click on the images as they are rather large.

 

[tsialex]

That's great! Thanks for that.

Let me show you what the motherboard looks like with the focus on the front and rear pins. Sadly I don't have a close up on the rear, but they look more or less the same. Is there anything that could be said about that? Please click on the images as they are rather large.

You removed the plastic mount of the fan connector, this is what a correct one should be:

 

[theStruggle]

You removed the plastic mount of the fan connector, this is what a correct one should be:

Aha! I can't remember there being plastic mounts...and also don't understand why I would remove them in the first place. Been burnt out for so long that I can't recall. So they are essential?

 

[tsialex]

Aha! I can't remember there being plastic mounts...and also don't understand why I would remove them in the first place. Been burnt out for so long that I can't recall. So they are essential?

It's what makes you mount the fan correctly and not backwards.

If you are in the US, maybe you should buy a new backplane, some are less than $70 with shipping on eBay, to install and test your own fans, you maybe burned the SMC micro controller mounting the fans backwards.

Anyway, you are in a conundrum and will need to buy at least one fan to start the troubleshooting.

 

[theStruggle]

It's what makes you mount the fan correctly and not backwards.

And there's the solution. The plastic mounts were gone for so long and I forgot the way
they were supposed to be mounted, not even the hint from the speaker pins got me to
think about that. Thank you so much! It's a stupid mistake on my part. Please don't rub it in!

However there's now another problem; the back fan is now on full blast from boot, I tried to
reset the SMC - but I might not have succeeded. I also tried the ASD and ran the fan tests
and the test fails to control the fan at all, as in the RPM's does not falter. However the front
fan controls just fine.

Installed SMC Fan controller and while the fan is going on full blast there is no info of it.
It says '0 rpm'.

Might this error be the one where you mentioned the SMC micro controller might have
been burnt?

 

[tsialex]

Might this error be the one where you mentioned the SMC micro controller might have
been burnt?

Possibly. Did you tried installing the front fan into the back assembly? Invert the fans into the assemblies, if after that still shows zero RPM for the exhaust fan, you will need a new backplane. If zero RPM changes to the intake, you will just need a new fan.

 

[theStruggle]

Invert the fans into the assemblies, if after that still shows zero RPM for the exhaust fan, you will need a new backplane. If zero RPM changes to the intake, you will just need a new fan.

I did two attempts, where the first attempt was useless because I would have gotten the same outcome, but it was still nice to see that the PC fan connected to the exhaust still did read 2000 rpm which is likely to be the max for that fan?

See the screenshots.

1. Removed the full blast fan and put a "NB-eLoop" pc fan into the exhaust slot (2000 rpm).
2. Put the full blast fan into the intake slot (0 rpm).

End conclusion:
It seems like the original fan is broken and has to be replaced.