2011 iMac fan pinout

Jul 6, 2013
Classic Mac
Mobile Phone
Hi guys

I really hope one or more of you can help me with this, i would really appreciate it!

I need pinouts for these 3 fans, or just one as they're probably the same anyway..

In order, it's the 27" iMac, 2011 model fans, CPU, ODD and Harddrive fans.

I can't make out what pins are what, as in, what's 12v, what's ground, what's the PWM signal if any..

At least two of these fans will be utilized if possible, or maybe just the one, but that's another very annoying issue of mine..

Any input will be greatly appreciated!! Thank you in advance!
Jul 6, 2013
Classic Mac
Mobile Phone
Alrighty then guys and girls, i found a thread on where a user called Masikakikairi, shared a pinout for some PowerMac fans for the OP.

And since the english weren't really something i understood fully (me being danish and all), i was not at all sure what either of them meant, as there was some sort of comment on the fans could run as a 3-pin fan in DC mode (Meaning the motherboard could control the fan through the BIOS and/or fan control software, for those who don't know what that means).


What i found out from the thread, was this:

O/P -> Feedback/Sense Typically yellow or green
VM/PWM -> Control wire Typically Blue
G -> Ground/Negative - Typically Black
VCC -> Plus/12v - Typically red

But! For these to run at all, you can't just connect them as mentioned above.

What you actually need to do, is:

O/P -> Yellow
G -> Black

Then the funky bit:
VM/PWM & VCC -> Red

Meaning the control wire (typically blue) is not used at all, so that the fan essentially is, as mentioned, working as a 3-Pin fan.

I hope this made sense, if not feel free to ask.

I'll post a couple of pictures if you guys are interested or for those who can't wait what i've got in store. ;)
Dec 14, 2016
dual w5580
dual r9270
I just came across this thread while looking at how to run a couple fans from a 2011 iMac 27 inch that we found in the recycling.

On the BFB0812HD -HM01 (610-0035) blower (optical drive/GPU): With label side up, in order from the 'bottom' of the label up:


On the BFB1012MD -HM00 (610-0064) (CPU fan): with label side up, in order from the bottom of the label up:


The labels are under the sticker of the fan, and can be hard to see.

For the GPU fan, in order to power it up you need to connect VM and GND to +12V and GND respectively.
The VM pin is NOT a speed control pin; it pulls ~200mA running, indicating this is the motor's power supply.
The Vcc pin is the PWM speed input - I tested this with a PWM generator and the fan speed can be modulated through this pin at about 30kHz though it was not particularly sensitive. It pulls about 10mA. You need to supply 12V PWM signals or it will not function.

For the CPU fan, I wasn't able to get it working with the PWM generator probably because the fan pulls too much current (14mA or more) on the PWM pin but using the same wiring scheme and the Vcc (PWM) pin pulled to 5v/12V, the fan will run at full speed.

It is rather loud on full speed but the motors appear to be 1-phase (two pole pairs, 'four' poles) sine-wave commutated. The sine wave commutation should reduce the vibration from the motor, and are not much less smooth than the MacMini fans' '6 pole' three phase motors.

Modulating the speed of these fans down will make them very silent and still move a decent amount of airflow. You can probably use the O/P pin with a pull-up resistor to voltage to obtain a waveform (2/4 pulse per rotation) to sense the speed of the fan.

Hope this is useful to someone.