In a message dated 08/20/2000 3:12:33 AM Eastern Daylight Time,
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<< Hi All,
     I would like thoughts from anyone using the Celeron 566-MHz Coppermine
 CPU on an ASUS CUBX motherboard and using the ASUS Probe V2.11 software for
 monitoring temperatures.
     ASUS claims to be able to monitor the CPU temperature of "compatible"
 CPUs, and the Coppermine CPUs are listed as "compatible", however, my
 Celeron 566-MHz CPU did not come with any thermal probe attached, nor did my
 supplier attach any, yet the software is giving me readings in the 40C
 range, which are well below realistic temperatures, which range up to 80C.
     To compound my perplexity, the Intel Data Sheets list NA (Not
 Applicable) for the Case Temperatures of the Coppermine CPUs and instead
 list the Junction Temperature as 90C!  Since I cannot measure the Junction
 Temperature and Intel does not list a Max Case Temp, what magic does ASUS
 use to probelessly "record" the CPU temperatures?  Did I miss out on the
 latest developments in thermodynamics technology?
     I bought a thermal probe with the intention of attaching it to the CPU
 but then realized that the ASUS CUBX motherboard had no provision for
 plugging it in and, even if it did, I still would not know to which
 temperature to set the alarm.
     I am concerned about adjusting the temperature alarm on my computer to a
 realistic setting, especially since I live in Florida, where the summertime
 ambient temperature is mostly in the 90s.
     I would appreciate any authoritative information available on this
 matter.
     Karl Kuller            [log in to unmask] >>

Hi,
  Intel adds a temperature detecting diode to the die of the CPU's they make.
  A silicon diode has about a .7 volt drop across it (before it starts to
conduct) at room temperature. This voltage changes by 25mV per degree C, so
by measuring the diode voltage drop, you can tell the temp of the CPU, with
no additional probes or other devices.
  Your temps in the 40C range are quite normal (just over 100F) when using a
good heatsink/fan, the junction temps you are referring to (90C) are maximum
temp ratings, though it is better to keep the CPU as cool as possible.
 The junction temperature refers to the diode junction temperature, which
shows the actual CPU silicon die temp, not the CPU case temp, which can be
several degrees cooler.
  I think a good setting for your temp alarm would be 10-20C (18-36F) higher
than the normal running temp. The CPU shouldn't ever get this hot during
normal operation, and this setting will still give you ample warning before
the CPU approaches the maximum allowable temps.

HTH,
Peter Hogan
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