Hi Folks
I hope these escapades prove informative (and hope this mail finally gets through!)
This is a sequel to my previous Emails (Pismo Sleeping/Booting Saga) (e.g. www.mail-archive.com/[EMAIL PROTECTED]/msg18290.html) about my PowerBook G3/400Mhz which wasn't reliably booting and sleeping.
Fortunately I had AppleCare extended last November (2003) for two more years
(A$384). Since then the DVD drive has been replaced twice (yes the "reliable" LG
DRN-8080B) and now I have had to deal with this current repair.
In short, it turns out, that the 400Mhz processor module (661-2386, P3589) had to be
replaced (I could trace down the former number but the latter number P3589 seems
mysterious!) which then solved the booting/sleeping problems; not my first guess
since the Pismo was running reliably otherwise.
Anyway, I had been playing with temperature monitoring (since the PowerPC 750
can estimate temperatures on the chip due to its Thermal Assist Unit (TAU)) and
had been largely using ThermoInDock (but also the excellent Temperature Monitor
(www.bresink.de/osx/TemperatureMonitor.html).
Normally these temperature monitors (using the TAU on the PowerPC 750) indicate
a temperature of around 30-40 Celsius (sometimes a little more if the CPU is busy).
However, with the new CPU installed, I am getting CPU TAU readings of 90-114 Celsius
(I also have an IBM 40GB GN Travelstar disk with SMART monitoring with temperatures
in the range of 25-45 Celsius, of course on chip temperatures may bear no relation).
Ambient air temperature is about 20 Celsius (inside with the heating on, it is Winter here!)
Some samples:
Temperature Sensors Date Time CPU TAU SMART Disk ------------------------------------------------- 2004-07-23 08:42:05 +1000 80.00 25.00 2004-07-23 09:42:05 +1000 100.00 42.00 2004-07-23 10:42:05 +1000 92.00 44.00 2004-07-23 11:42:05 +1000 92.00 42.00 2004-07-23 12:42:05 +1000 92.00 42.00 2004-07-23 13:42:05 +1000 92.00 43.00
There is a huge caveat regarding the TAU accuracy:
"Some older G3 or G4 systems can be equipped with processors containing a so
called "Thermal Assist Unit (TAU)". This is a technique to acquire temperature
values directly on the chip die and compute it by the processor itself. However,
this technology is very inaccurate and only works correctly if each processor is
calibrated. Motorola specifies that the readings supplied by such processor
types can be off by 12 degrees Celsius (21,6 degrees Fahrenheit) from the actual
values. For IBM G3 processors there can even be a difference of 20 degrees
Celsius (68 degrees Fahrenheit) between the measured and the true values. Due to
this problem, the processor manufacturers have disabled the TA Units for later
product generations. Up-to-date versions of the G4 series no longer support
temperature measurement on the chip die. Here, real sensors have to be used."
The original processor in the Pismo was definitely a previous generation
(if the numbers in parentheses indicate generation) with the designation
PowerPC 750 (83.0) 400Mhz (I think, year 2000 vintage) while the current
processor module has an updated numbering: PowerPC 750 (83.2) 400Mhz. Ideas?
I believe that the Pismo uses IBM PowerPC parts (since the Motorola equivalent
is called an MPC750) so it might be:
1) what I am seeing is a truly inaccurate uncalibrated number for the CPU temperature
and it is indeed running at a much lower temperature (e.g. 40 Celsius).
2) However the link www.xlr8yourmac.com/tips/G3_temp.html mentions that
it is possible to install the heatsink on the chip with poor thermal conductivity.
So it could be that the CPU is running hot (but perhaps not as hot as 90-100 Celsius
because the TAU is inaccurate) due to poor installation ... Is this reasonable?
Should I get the AppleCentre to reinstall with more thermal paste (assuming they
used any?).
I am thinking of checking with the AppleCentre where I hope I can speak to the
technician who did the reinstall. Or should I just happily use the laptop till
it fries. Externally the Pismo doesn't feel much hotter than normal (the base
of the unit is always the warmest part) ... Hmmmm ... what to do ???
Reasonable suggestions Welcome!
Harry.
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