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Re: how to limit a CPU temperature?

From David Christensen <dpchrist@holgerdanske.com>
Newsgroups linux.debian.user
Subject Re: how to limit a CPU temperature?
Date 2023-04-10 01:50 +0200
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References <GihA5-E2o-5@gated-at.bofh.it> <GirJ7-Klc-1@gated-at.bofh.it> <GitKV-LCM-3@gated-at.bofh.it>
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On 4/8/23 20:11, Mark Allums wrote:
> On 4/8/2023 8:01 PM, David Christensen wrote:
>> On 4/8/23 07:17, songbird wrote:
>>>    i have a program that has changed it's behavior to suddenly
>>> become a CPU hog (while doing something simple like uploading
>>> files for my website).  probably a bug, but it got me to
>>> wondering how i could limit the CPU temperature to a range
>>> well below the maximum that kicks in by the CPU itself.
>>>
>>>    i have an intel processor and it has the MAX which does
>>> prevent it from going higher (100C), but i'd like to keep it
>>> at 70C or lower.
>>>
>>>    i've been trying to find anything that will let me set this
>>> but no luck yet in my searches.
>>>
>>>    thanks!  :)
>>>
>>>
>>>    songbird
>>
>>
>> Assuming the computer had a proper thermal solution when assembled, 
>> the 100 C processor temperature indicates that the thermal paste 
>> between the processor and its heat sink has gone bad.  I suggest 
>> replacing it with silver-based thermal paste.
>>
> New paste yes, silver no.  That's out-of-date.  Silver is conductive. 
> Silver paste is not superior to Thermal Grizzly Kryonaut or Arctic 
> (maker of the most popular silver paste) MX-6. You want non-conductive, 
> non-capacitive paste.
> 
> 
> Mark Allums


Thank you for pointing out advances in thermal paste since the last time 
I used such.  STFW the two brands you mention do seem to be the current 
"top of the charts":

https://en.wikipedia.org/wiki/Thermal_paste

https://www.tomshardware.com/best-picks/best-thermal-paste

https://www.tomshardware.com/news/artic-mx6-thermal-paste

https://www.thermal-grizzly.com/en/products/16-kryonaut-en

https://www.arctic.de/us/MX-6/ACTCP00079A


I agree that getting paste where it does not belong during installation 
is a problem; thermally, electrically, and chemically.  "non-conductive, 
non-capacitive paste" should mitigate damage should this risk occur. 
Thankfully, I have not created such a mess; and the ones I have cleaned 
did no apparent damage.


The last time I installed (silver-based) thermal paste, I seem to recall 
that the manufacturer's directions were to apply a bead the size of a 
grain of long-grain rice to the center of the processor case and then 
seat the heat sink straight down.  I believe I took one such joint apart 
shortly after installation, and the paste had spread into a circular 
area with a diameter of ~80% of the processor top.  I will be curious to 
see the pattern after a long period of use, if and when I take one of 
those joints apart again.


I do not want paste oozing out of the sides of the joint, so I have 
resisted the urge to use more paste or enlarge the application pattern.


I do not want air bubbles, so I have resisted the urge to spread the 
paste.  However, Thermal Grizzly recommends this technique in their 
application guide:

https://www.thermal-grizzly.com/images/downloads/TG-ApplicationShortGuide.pdf


I have installed a few Intel "boxed" processor kits that included heat 
sinks and fans.  The heat sinks had a fine pattern of thermal paste in 
rows with empty furrows in between.  The pattern covered the entire 
mating surface.  The paste was nearly solid and was silver in color.


Looking beyond spillage, putting a insulator (non-conductive thermal 
paste) between two conductors (metal heat sink and metal processor case) 
is how you form a capacitor:

     https://en.wikipedia.org/wiki/Capacitor#Parallel-plate_capacitor

     The simplest model of a capacitor consists of two thin parallel
     conductive plates each with an area of A separated by a uniform gap
     of thickness d filled with a dielectric with permittivity ε . It is
     assumed the gap d is much smaller than the dimensions of the plates.
     ...
     ... the highest capacitance is achieved with a high permittivity
     dielectric material, large plate area, and small separation between
     the plates.
     ...
     The maximum energy is a function of dielectric volume, permittivity,
     and dielectric strength.


Following the link "permitttivity":

     https://en.wikipedia.org/wiki/Permittivity

     In electromagnetism, the absolute permittivity, often simply called
     permittivity and denoted by the Greek letter ε (epsilon), is a
     measure of the electric polarizability of a dielectric. A material
     with high permittivity polarizes more in response to an applied
     electric field than a material with low permittivity, thereby
     storing more energy in the material. In electrostatics, the
     permittivity plays an important role in determining the capacitance
     of a capacitor.


So, it would seem that "non-capacitive" thermal paste is thermal paste 
with low electromagnetic absolute permittivity.


Does anyone have any ideas or explanations regarding forming a capacitor 
out of the processor heat sink and the processor case by using a 
non-conductive paste versus forming an electrical connection by using an 
electrically conductive thermal paste?  Or, a "real world" joint using a 
thermal compound with electromagnetic impedance that varies with 
frequency and/or intensity of the imposed electromagnetic field? 
Notably, at frequencies of 66 MHz (processor external bus) and ~1 to ~5 
GHz (processor internal)?


David

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Thread

how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 16:20 +0200
  Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 16:30 +0200
    Re: how to limit a CPU temperature? "tv.debian" <tv.debian@googlemail.com> - 2023-04-08 16:50 +0200
      Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 18:00 +0200
        Re: how to limit a CPU temperature? "Andrew M.A. Cater" <amacater@einval.com> - 2023-04-08 18:20 +0200
          Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 20:40 +0200
    Re: how to limit a CPU temperature? "Jeremy Nicoll" <jn.ml.dbi.73@letterboxes.org> - 2023-04-08 17:00 +0200
      Re: how to limit a CPU temperature? davidson <davidson@freevolt.org> - 2023-04-08 17:20 +0200
        Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 17:50 +0200
      Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 18:10 +0200
        Re: how to limit a CPU temperature? Vincent Lefevre <vincent@vinc17.net> - 2023-04-13 16:30 +0200
    Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-11 02:20 +0200
      Re: how to limit a CPU temperature? Max Nikulin <manikulin@gmail.com> - 2023-04-11 03:30 +0200
  Re: how to limit a CPU temperature? tom@myposts.ovh - 2023-04-08 16:30 +0200
    Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 18:10 +0200
  Re: how to limit a CPU temperature? Emanuel Berg <incal@dataswamp.org> - 2023-04-08 17:20 +0200
    Re: how to limit a CPU temperature? songbird <songbird@anthive.com> - 2023-04-08 18:00 +0200
      Re: how to limit a CPU temperature? "Jeremy Nicoll" <jn.ml.dbi.73@letterboxes.org> - 2023-04-08 18:10 +0200
      [OFFTOPIC] Re: how to limit a CPU temperature? Stefan Monnier <monnier@iro.umontreal.ca> - 2023-04-08 19:00 +0200
        Re: [OFFTOPIC] Re: how to limit a CPU temperature? Emanuel Berg <incal@dataswamp.org> - 2023-04-08 19:20 +0200
          the front (was: " Re: [OFFTOPIC] Re: how to limit a CPU temperature?") Emanuel Berg <incal@dataswamp.org> - 2023-04-08 19:30 +0200
            Re: the front (was: " Re: [OFFTOPIC] Re: how to limit a CPU temperature?") Jeffrey Walton <noloader@gmail.com> - 2023-04-08 20:00 +0200
              Re: the front (was: " Re: [OFFTOPIC] Re: how to limit a CPU temperature?") Emanuel Berg <incal@dataswamp.org> - 2023-04-08 20:10 +0200
        Re: [OFFTOPIC] Re: how to limit a CPU temperature? Jeremy Ardley <jeremy@ardley.org> - 2023-04-09 01:00 +0200
  Re: how to limit a CPU temperature? Tixy <tixy@yxit.co.uk> - 2023-04-08 22:10 +0200
  Re: how to limit a CPU temperature? Ash Joubert <ash@transient.nz> - 2023-04-09 02:30 +0200
  Re: how to limit a CPU temperature? David Christensen <dpchrist@holgerdanske.com> - 2023-04-09 03:10 +0200
    Re: how to limit a CPU temperature? Mark Allums <maa@allums.com> - 2023-04-09 05:20 +0200
      Re: how to limit a CPU temperature? David Christensen <dpchrist@holgerdanske.com> - 2023-04-10 01:50 +0200
  Re: how to limit a CPU temperature? Darac Marjal <mailinglist@darac.org.uk> - 2023-04-09 14:30 +0200
    Re: how to limit a CPU temperature? Emanuel Berg <incal@dataswamp.org> - 2023-04-09 14:40 +0200
  Re: how to limit a CPU temperature? David Christensen <dpchrist@holgerdanske.com> - 2023-04-10 04:20 +0200

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