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Super LFM question


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Hi All,


Does anyone know why Super LFM is not enabled for Macbook 13" Aluminum late 2008 model?


I just found this out after I installed Bootcamp and Windows 7 on my Macbook 13" with P8600 2.4Ghz CPU 2GB RAM and 250G HDD after more than a year of using it.

After I installed the CPU monitoring widget on Windows 7 and CPUZ, I noticed that the lowest Freq that my Macbook operates even with <5% CPU load is only 1.5Ghz and VID @1.0V.

I installed Coolbook on OSX to confirm what I saw on Windows. I was surprised that SLFM is not visible in Coolbook which is the same result I got from Windows 7 CPU monitoring widget and CPUZ.


I checked with our local Mac support and they got the same results for all of Macbook 13" Aluminums late 2008 model. SLFM is not visible on Coolbook which means, it is not enabled.


I tried to install Coolbook on my wife's Macbook Pro 13" 2010, which has the same spec, P8600 2.4Ghz CPU and 250G HDD. The only difference is the memory which is 4GB RAM. There, SLFM is enabled and works just fine, running at 798Mhz @0.875V.


Below is what I got from Coolbook for comparison. Or you can also refer to attached Coolbook screenshots. As you can see the late 2008 Macbook has no SLFM info.




SLFM - Super Low Freq Mode

LFM - Low Freq Mode

HFM GV - High Freq Mode (Geyserville/Speedstep)

HFM - High Freq Mode


Macbook 13" Aluminum (Late 2008) P8600 2.4Ghz 2GB RAM 250GB HDD


Freq VID

SLFM -- --

LFM 1596Mhz 1.0000V

HFM GV2 1862Mhz 1.0500V

HFM GV1 2128Mhz 1.1000V

HFM 2394Mhz 1.1375V


Macbook Pro 13" Aluminum (2010) P8600 2.4Ghz 4GB RAM 250GB HDD


Freq VID

SLFM 798Mhz 0.8750V

LFM 1596Mhz 1.0000V

HFM GV2 1862Mhz 1.0500V

HFM GV1 2128Mhz 1.1000V

HFM 2394Mhz 1.1375V


Can anyone please help confirm if this is really the case for Macbook 13" late 2008 model?

Because I checked the Intel P8600 Datasheet and SLFM should always be enabled. Otherwise, it will affect the battery life as well as long term reliability of the CPU.


I would appreciate if the Macbook and Macbook Pro owners in this forum can help confirm using Coolbook the status of Super LFM in your own Macbooks. You may use any other tool in checking the SLFM and share it with us if you believe it is more reliable and better than Coolbook. Thanks.



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