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MIKX

macrumors 68000
Original poster
Dec 16, 2004
1,815
691
Japan
I have replaced my cMP 4,1>5,1 Apple standard 120mm PSU fan with the Noctua NF A12x25 120mm PWN fan and have also installed The Noctua NF-FC1 PWN Fan speed controller. I am happy to report that both the Noctua fan and the fan speed controller are working perfectly.

EDIT : I cleaned up the cables ! Everything is working. The Noctua fan is now at 1050 RPM as a test for summer
temps. It is working silently. @ 1050 rpm with ambient @ 26°C in iStats menus the PSU temp is 36°C.
Both of the DVD drive doors are taped OPEN to allow more airflow.


00 PSU & PCI overview less textJPG.jpg



LINKS :

Noctua NF A12x25 120mm fan for cMP PSU on Amazon.com https://www.amazon.com/Noctua-NF-A1...ywords=noctua+nf-a12x25&qid=1589390335&sr=8-9

Noctua NA-FC1 PWN fan speed controller on Amazon.com https://www.amazon.com/gp/offer-listing/B072M2HKSN/ref=dp_olp_afts?ie=UTF8&condition=all

01 Noctua NF-A12x25 120mm Mac Pro PSU fan.png
02 Noctua Fan controller NA-FC1.jpg


I have tested changing the 120mm Noctua NF A12x25 fan's speeds from ( EDIT ) 800 ~ 1,200 rpm using the Noctua NA-FC1. Response in changing RPM is near instantaneous

Istats Menus May 14th. 2020.jpg






a. WHY ?
Firstly, my 2009 4,1>5,1 cMP is now over 11 years old ! . .and because replacing the Apple PSU fan is a pain
as the 4,1 / 5,1 PSU fan's power cableruns UNDER the cMP's backplane/motherboard. Luckily I have bypassed this
limitation ( see " b " )
I live in Japan which has a long. hot ( up to 40°C ) 7 humid summer- late July to late SeptemberFA.
My 4,1>5,1 cMP is now 11 years old but still remains my faithful & favourite desktop computer.
Due to re-routing the PSu fan’s power cable I no longer need to remove the cMP’s backplane should I need to
again replace the PCU fan.
BONUS : I now have TWO working PSU fans - I’m keeping the original Apple PSU fan as a backup spare.
I have since proven that with just removing the power supply ( 4 screws ) I can now replace the PSU fan & reboot in
30 minutes.

b. Why is the PSU fan's cable routed UNDER the backplane/motherboard ?
Apple decided that to remove/replace the 4,1/5,1 PSU fan the the backplane MUST be removed.
This is a fallacy, I ran the Noctua’s power cable down through the small gap on the far left side under the DVD/PSU area.
Problem solved though for the very first time/replacement the BACKPLANE/MOTHERBOARD still needs to be removed ; allow the cable re-routing.
04,1 RE-route cable basic.jpg


c. Fan rubber retaining grommets removal.
These grommets CAN be removed fairly easily.
Requirements : TWO pairs of slim long, ‘needle nose’ pliers
Using the pliers, grab EACH opposite end of a grommet and then STRETCH it from both ends !
Result: The grommet, as it is stretched becomes thinner in diameter and can then be ‘edged’ back through the
Fan ‘grommet hole’. I have successfully removed 6 grommets from old cMP 2,1 fans without causing ANY damage.
Proof
03 Previously removed grommets 02.JPG

================================================================

HOW TO REPLACE the 4,1 / 5,1 PSU fan with Noctua A12x25 120mm fan. ( first time ).

1. Remove the power supply= 4 screws

2. Remove the backplane/motherboard. I VERY STRONGLY SUGGEST that first timers watch this video
prior to attempting this.
The only HARD PART is removing the CPU Tray fan assembly which requires so wiggling of the INTAKE & EXHAUST
fans. NOTE : Disconnect the INTAKE & EXHAUST fan connector from the BACKPLANE.
Removing the backplane is not a trivial operation but is definitely DOABLE in about 30 ~ 40 minutes provided you make a “ to do “ list
And work slowly and carefully. In my case, it was my first time and I do admit to some apprehension but in the end .. =success !

3. Remove the GROMMETS using TWO sets of slim, needle need pliers. ( follow the directions in “ paragraph “ c” above.

4. RE-ROUTING the Noctua NF A12x25 120mm fan CABLE.
Now that the backplane has been removed you can retract the existing PSU fan cable.
Install the Noctua fan
Run the Noctua NF A12x25’s power cable down through the small space on the far left side of the DVD/PCU space.
4.1 IMPORTANT :
The Noctua fan cable socket ( where it connects to the backplane) - has TWO raised locator guides !
ONE of these needs to be SHAVED OFF )
Use a hobby knife with a new blade. This SHAVING will allow the cable to 100% allow it to connect to the
backplane PSU power socket.

05 SHAVE OFF.jpg

=======================================================
I will continue to finish this guide as time allows. I am recovering from a broken hip surgery, I need more sleep than usual.
=======================================================


In the meantime . . . . .

These cables are included in the NA-FC1 PWM speed controller kit
Noctua-NA-FC Page 01.jpg


Noctua-NA-FC Page 02 controls diagram.jpg
02.1 Noctua NA-FC 1 kit contents.png
 
Last edited:
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This is a more comprehensive pic of my 4,1>5,1 setup with the Noctua 120mm fan installed & running with the Noctua NA-FC1 PWN speed controller running the fan at 1-50 rpm as a test.
00 PSU & PCI overview 2 SML.jpg
 
This is a more comprehensive pic of my cMP 4,1>5,1 set up. ready for Japan's long, hot & humid summer 2020
00 PSU & PCI overview 2 SML.jpg
 
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Interesting! I have an 2009 MP as well and I've been wondering about the fans since the CPU upgrades force more rpms into the now 11 year old fans. Do you plan on doing anything similar for the Intake and Exhaust fans?
 
No, not at the moment, everything is running slow & cool. I'd rather buy a dual 5,1 = much easier to set the CPU tensions.
 
Last edited:
No, not at the moment, everything is running slow & cool. I'd rather buy a dual 5,1 = much easier to set the CPU tensions.

Well it's a little late now, I went that war last week! 😄 In all seriousness I've had the thing since new so not going to give up now.
 
This is a video showing the Noctua NA-FC1 4 pin PWM fan controller working in a Win PC.


Since installing my NA-FC1 to control my Noctua NA-A12x25 120mm Mac Pro replacement PSU fan I couldn't be happier.
I have mine installed in the DVD drive cage area as I have no drives at all installed there to increase airflow to the PSU.

There are TWO SATA connectors in the DVD drive cage area, I use one of them to power the Noctua NA-FC1.

NOTE : When i FIRST installed the Noctua PSU fan I re-routed the fan cable through the small opening on the far left - above SATA Bay 1 so that now should I need to take the fan out I DO NOT NEED to remove the Mac Pro's backplane = motherboard.
Now I can replace the PSU fan from start to finish in about 20 minutes after just removing the PSU ( 4 Torkex screws. )

Better, now i have TWO working 4,1/5,1 PSU fans with the original Apple ( 11 years old ) fan as a spare.

The Noctua 120mm NA-A12x25 is virtually silent at any speed I throw at it via the NA-FC1.

Japan's hot & humid summer ( I live in Japan ) is approaching rapidly. This year, along with my NorthBridge Tdiode cooling ( USB powered 16.4 CFM fan ) up and running . . . I am ready !

Today I thoroughly de-dusted my 4,1>5,1
 
Quick question, do you have to shave off one of the locking nubs on the NA-FC1 controller sata connection in order to attach it to the SATA-2 cable in the drive bay?
 
Quick question, do you have to shave off one of the locking nubs on the NA-FC1 controller sata connection in order to attach it to the SATA-2 cable in the drive bay?
Yes.
I DID put this photo in Post #1


05 SHAVE OFF.jpg
 
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