[Tfug] Got an odd one: laptop AMD CPU stuck at 800mhz, won't jump to 1, 600

John Gruenenfelder jetpackjohn at gmail.com
Sat Jan 21 13:47:03 MST 2012

I would guess that for some reason the kernel has chosen an incorrect
frequency scaling driver.  Speedstep proper is only on Intel CPUs, but
there are equivalent drivers for AMD Mobile and AMD64 CPUs.  It could be an
incorrect choice there.  There is also a more modern ACPI P-States
frequency scaling driver that I suppose could have been loaded.

The kernel config help also still says that AMD CPUs should use the
conservative CPU governor instead of the ondemand governor.  I don't think
this is true on the newer chips, though.  And, in any case, this particular
module choice shouldn't affect your direct choice of speeds.

That said, I suppose if you inadvertently had the powersave governor
loaded, it might restrict you to the lowest speed.

As for other slowness possibilities... maybe your distro has incorrectly
decided to use a 3D desktop but the OSS Radeon driver is only doing
software 3D via Mesa?  The Radeon driver has gotten much better now,
though, and even supports 3D on my RV770 chip (I can't even get the
proprietary driver to work correctly anymore).  But it's something to check.

--John Gruenenfelder
Systems Manager, MKS Imaging Technology, LLC.
Try Weasel Reader for PalmOS -- http://weaselreader.org
"This is the most fun I've had without being drenched in the blood of my
--Sam of Sam & Max

On Jan 21, 2012 11:20 AM, "Jim March" <1.jim.march at gmail.com> wrote:
> Folks,
> Somebody gave me a Dell Latitude D531, has an AMD CPU (dual-core
> TL-50) that can "speedstep" between 800mHz and 1.6gHz.
> I dropped my existing hard disk from another laptop over to it, fired
> it up.  Existing install is Mint 12, 32bit (similar to Ubuntu
> Oneiric).
> Seemed ghastly slow on the "new" machine.  I noticed that my CPU
> frequency scaling toolbar thingie that I always run showed it locked
> to 800mHz.  This tool can also show available speeds and if you want,
> lock the CPU to one speed or another.
> It would not accept a command to crank it up to 1.6.  Literally wouldn't
> I tried turning off Speedstep in the BIOS, locking it to high speed.
> No joy - the frequency scaler broke at that point but performance
> testing of, say, flash videos (plus slow boot times and more) showed
> the speed was still stinking.
> OK, what the hell?
> Has anybody seen anything like this before?
> I'm going to try swapping the RAM over (2gig PC5300 on both my old and
> this "new" lappy) and see if that helps?  But...I don't think that's
> it.
> What would cause the CPU to be locked into stupid mode?
> What else...video card on the old machine (physically falling apart!)
> is an Intel 965/X3100 type, new (the "slow machine") is an ATI 1270.
> The ATI video drivers seem to be working OK (open source Radeon).
> Jim
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