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> Cpu Fan Speed Control Via Smc Key Programming
post Feb 23 2012, 05:18 PM
Post #1

I need some help.
The CPU fan of my iMAC, sometimes, runs at full speed of 4200 RPM.
It is very annoying. I am trying to lower the fan speed through the SMC key programming.

At this moment, some of the SMC key values are below:

F2Ac [fpe2] 4148 (bytes 40 d0)
F2Mn [fpe2] 1197 (bytes 12 b4)
F2Mx [fpe2] 4200 (bytes 41 a0)
F2Tg [fpe2] 4200 (bytes 41 a0)
FS! [ ] no data

The problem that I have is that it seems like I can not change the F2Mx and F2Tg values.
The Fan force bit, FS!, is not readable.

Does anyone know how to control the max fan speed manually?

post Feb 23 2012, 05:56 PM
Post #2
Update firmware.
Or no solution AFAIK.
i3-2120 GA-H61M-S1 UEFI, Radeon HD6670-UEFI, ALC887(VoodooHDA 2.8.7), OS⌘10.9.5, OS⌘ 10.7.5 Clover HWSensors3 Realtek LAN v3.1.2
post Apr 8 2012, 05:39 AM
Post #3
I've serviced a few iMacs - those things can tend to build up dust on the ambient sensor (and lots of other parts) - I would recommend running the appropriate ASD, and making sure any temp sensors and fans don't have a significant amount of dust buildup which could cause a performance decline. Good luck.
post Mar 16 2013, 07:50 AM
Post #4
Firmware update is the best solution to this.
post Mar 23 2013, 03:19 AM
Post #5
QUOTE (baudinetuwilliam @ Mar 16 2013, 07:50 AM) *
Firmware update is the best solution to this.

This worked for me. Just do the update!
post Nov 24 2013, 01:09 AM
Post #6
What firmware should I have now?

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