From: AC Brown (acb_at_acbrown.com)
Date: Mon Jul 17 2000 - 17:03:18 EDT
Date: 2000 Jul 17
To: <thinkpad_at_cs.utk.edu>
From: AC Brown <acb_at_acbrown.com>
Subj: T20 Evaluation: Case Temperature
There are have been a number of questions on this board concerning the
new IBM A20 and T20 computers, especially compared to previous models.
I'm a long time Thinkpad user (750C, 755CD, 560, and 570), and I've had
experience with Toshiba, Compaq, and Powerbook notebooks. I recently
acquired a new T20 (2647-84U, Windows 2000), so I thought I'd post my
impressions after almost three weeks of use. I plan several postings on
the various aspects of the T20, especially compared with my previous
Thinkpads.
THERMAL CHARACTERISTICS
I measured the temperature at the hottest location on the bottom of the
T20 case using a small disk thermistor taped to the case with "Magic"
transparent tape and connected to a thermistor thermometer (Omega
Engineering 700C). For these tests, the computer was running on AC
power. Most of the measurements were made with the computer
mounted on the T20/A20 port extender.
When the computer is first powered on, the case temperature rises at
about 1 C per minute until it reaches about 40 C, when the fan speeds up
and maintains the temperature at 40 +/- 1 C most of the time. The fan
is very quiet.
However, once in a while, perhaps every 30-90 minutes, the temperature
rises rapidly for a few minutes to 46 C or so before the fan brings the
case down to the 40 C range. I consider these temperature spikes a
defect for two reasons. First, rapid temperature cycling of 5-6 C and
the resulting thermal expansion/contraction cannot be good for the
electronics. Second, 45 C is the approximate threshold for causing
cutaneous pain and injury.
I contacted the IBM Help Center (800-772-2227) and asked about the
temperature specifications for the T20 case but they had no information
on the subject. I said that if the case normally got to 45 C or higher,
a notice should accompany the computer warning against placement on bare
skin because of possible injury. They suggested I return my computer
for service but I've not done so yet.
I'm interested in whether these temperature spikes are the result of a
design defect or a problem with the thermal control system only in my
computer. Has anyone else had problems with excessive heat? If the
case becomes painful to touch, it's too hot!
Also, I measured the internal temperature near the case hot spot by
taping the thermistor probe to the middle of a PCCard (an Adaptec 1480A
scsi controller) in the computer's top PCCard slot; the bottom slot was
empty. The PCCard peaked at 52.9 C and showed rapid swings of 10 C in
7-10 minutes. The high temperature and thermal excursions seems to me
to be likely to lead to problems, but I've no hard data on the matter.
Any responses on T20/A20 case temperatures would be appreciated.
AC Brown
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