Talk:Pentium M undervolting and underclocking

Hei Thinker,

according to my notion of the character of this page, i thought it should possibly be renamed to something like "How to lower voltage and clock speed on Pentium M processors" ("lower" might be replaced by "finetune" or "manually lower" or "tweak" or something else expressing more the expert audience of the article). This has the following advantages:

• complies with the naming scheme ;-)
• has words more likely to be found in google (voltage vs. undervolting; clock, speed vs. underclocking)
• Are undervolting/underclocking proper english words anyway?
• Follows a scheme of "from general to specific". The topic of the article is underclocking/undervolting. That it's for Pentium M processors is kind of secondary to that.

What do you think? I can do it if you agree.

Wyrfel 00:21, 21 Oct 2005 (CEST)

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Good points. Personally I'm fond of short technical titles, but I agree about accessibility and consistency with the rest of the site. I have a feeling (though no proof) that the underclocking doesn't really work (as I noted recently), so how about "Reducing voltage on the Pentium M processor" for now?

BTW, "underclocking" is pretty standard techie jargon (and a clear parallel of the well-known "overclocking"). "Undervolting" is somewhat less common, though I've seen it in use.

--Thinker 00:55, 21 Oct 2005 (CEST)

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Which patch to use?

Since I might find the time to fiddle around with reducing the power consumption further, I wonder which of the 3 alternatives works best. Any recommendations?

--spiney 11:05, 21 Dec 2005 (CET)

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They all work... I think Alternative 2 is easiest to use.

--Thinker 13:06, 21 Dec 2005 (CET)

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Init Script

Hi. I'm the author of the SysFS patch of "Alternative 2"

I have recently seen that someone has added your init script to my wiki page on gentoo-wiki. But unfortunatly this guy has removed all the exisiting content of the page at the same time. So a few hours later an admin of the site as reverted the page to its previous state.

Well that was just for the story of how I came to your wiki page. I just wanted to say That I have adedd again the init script to my page. It's a nice thing. A lot more "gentoo spirit" that what I was using before (that is adding some code in /etc/conf.d/local.start)

I have made some modifications to the init script before adding it on my wiki page. So maybe you want to have a look at it.

Cheers! --Bdz 23:26, 10 Jan 2006 (CET)

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Trouble loading modules

If you receive the error after applying the bdz patch:

    FATAL: Error inserting speedstep_centrino
   (/lib/modules/2.6.15.4/kernel/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.ko): No such device

be sure you have included "ACPI tables" for decoding valid frequency - voltage pairs.

Also, note you may have to manually "modprobe" the speedstep-centrino during your boot sequence. For some reason it won't autodetect on my debian sid system.

Underclocking results in a *noticably* cooler processor, approximately 3-5 degrees, which is often enough to have the fan stop (now 43 deg basal temp on my lap.) The battery life boost is much more modest, I'm down to 17.5 W/h now with everything off.

--gsmenden 23:50, 12 Feb 2006 (EST)

Undevolting a Core Duo

I have a Core Duo T2500, according to https://www.dedigentoo.org/trac/linux-phc/wiki/IntelCoreLimitationsOfLinuxPHC0_2_X, undevolting does not work really good, but the info is quite old too. So I want to ask if somebody is running an undervolted Core-CPU and has success with longer battery life and lower fan usage?

--Zhenech 14:45, 14 February 2007 (CET)

VID-only tables are useless

Please don't publish only VID data. You also need to publish the FID, because not all BIOSes/OS combinations allow one to select every possible frequency step, and users will later need to find out which FID correspond to each VID...

--hmh 20:30, 7 September 2007 (UTC)

Observation: fid:vid for a processor family is similiar i have two machines with p-m dothan processor (x41t 1.5 ghz LV and x32 1.8ghz) and it seems that for any given frequency (FID), stable voltage (VID) is very similiar, if i get my hands on some banias based thinkpad, i will check if that theory extends there

--KotCzarny 03:16, 17 November 2007 (UTC)

Voltage and frequency correlate

Transistors operate faster at higher voltages, allowing overclocking, and making it difficult to cool these cpu´s, as both higher voltage and frequency increase the heat loss. That is also true in the other direction: Lowering the frequency lets your cpu operate stable at lower voltages, but only lowering the voltage very likely makes it unstable. If it works anyway, fine, but be aware of the correlation of f_max and voltage. ~~Maxus