Thinkpad Thermals

[Jesse Guardiani]

Kevin Oberman wrote:

>> From: Jesse Guardiani <jesse at wingnet.net>
>> Date: Fri, 04 Mar 2005 13:01:21 -0500
>> Sender: owner-freebsd-mobile at freebsd.org
>> 
>> Howdy!
>> 
>> My IBM Thinkpad A30p's ATI video chip got cooked last year,
>> leaving me with an unreadable screen full of artifacts. I
>> finally bought a replacement mobo a few days ago and installed
>> it this evening. It's now running artifact free! Yay!
>> 
>> Anyway, I'm no longer running FreeBSD on this laptop. I'm
>> currently running Gentoo Linux. But it would be trivial
>> to switch back if needed.
>> 
>> I'm using gkrellm under linux to monitor my CPU temp, and
>> I'm noticing that it runs quite hot. The fan doesn't kick
>> in until the CPU hits 80C! That's a little too close for
>> comfort, IMO.
>> 
>> I think I remember seeing other posts from Thinkpad users
>> mentioning high temps under ACPI. Has anyone found a way
>> to cool these things down?
> 
> Jesse,
> 
> Is it running at or near 80C when idle, when in typical use, or when
> building something BIG (CPU running at >95% for minutes).

More or less idle. It fluctuates between 70C and 80C. Just playing an
MP3 I'm at 77C right now. Is this normal acceptable temp for a thinkpad?
Or should I be targeting the 40C range like I do with my desktop machines?


> I believe that the A30p is a P4-M CPU. It will turn itself off (hard,
> like a power cut-off) before the CPU dies, but that is NOT a good
> thing. That does not happen until the CPU reaches a frightening 135C.

Actually, I think mine is a P3-M at 1.2ghz. It uses PC133 SODIMMs, and
/proc/cpuinfo reveals this:

Intel(R) Pentium(R) III Mobile CPU      1200MHz

I think it's the A31p that uses a P4-M.


> If you are running 5-Stable or 6-Current you should load cpufreq and
> acpi_perf. These will give you a large number of CPU "frequencies"
> visible in dev.cpu.0 and settable in dev.cpu.0.freq. This provides
> fine-grained control.

I asked this question here mostly because I know a lot of people on this
list run Thinkpads, and I remember more than one complaining about cooling
issues.

Again, I no longer run FreeBSD on this laptop. I run Gentoo. Linux has
various different daemons capable of throttling the CPU though, and I
currently have an "on-battery" runlevel setup that runs the speedfreq
daemon with a preference for "powersave". I could install something in
my default "on-AC" runlevel that regulates CPU based on load even when
on AC...

But... is 80C normal under load? Running a frequency daemon won't change
the under-load temp unless I cap the horsepower or introduce some sort
of temp related frequency feedback control as you describe below.

Hmmm... well that's interesting: Just to test it out, I unplugged the
AC and ran it for a while, still playing the same MP3. It leveled out
at 66C in the "powersave" profile, which means that the CPU is running
at just 799.457mhz instead of 1199.185mhz (performance).

Is 66C acceptable temp for a laptop? It's definitely a better temp, but
It would really stink if my 1.2ghz had to be run at just 800mhz all the
time to avoid cooking things.


> Yo can also look at hw.acpi.0.thermal for _PSV and _CRT. _PSV is the
> temperature at which the CPU should start to slow down to moderate the
> temperature. _CRT is the point at which alarms are sounded and the OS
> should start a clean shutdown. If there is no cooling problem _PSV
> should keep the temperature from ever reaching _CRT. You will note that
> these temperatures are WAY under 135C, but the 135C cutoff is intended
> for catastrophic failures (like a broken/improperly installed heat sink)
> and assumes that the temperature rose very quickly. It is not intended
> that the CPU should run at that sort of temperature normally.
> 
> FreeBSD is still working on support for all of this, but it's getting
> much closer. The addition of powerd to Current is a big step, but it is
> probably not quite ready for prime time and is disabled by default. Nate
> just committed it to current a few days ago and I just installed it
> yesterday, so I have no experience with it.
> 
> Bottom line is that as long as the temperature stays below _PSV under
> heavy load, you should not be concerned. If it exceeds _PSV for very
> long, you might want to reduce dev.cpu.0.freq a bit. If you ever hit
> _CRT, dow something quickly. FWIW, my system has _PSV at 86.5C and _CRT
> at 94.0C, so 80C is really not that hot, though my thigh does not agree
> when my laptop is literally on my lap.
> 
> As always, I am not really an expert on all  of this and I can hope that
> Nate or someone else will correct any errors in this.

-- 
Jesse Guardiani, Systems Administrator
WingNET Internet Services,
P.O. Box 2605 // Cleveland, TN 37320-2605
423-559-LINK (v)  423-559-5145 (f)
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