[Debian-eeepc-devel] Temporarily disabling lid-close-suspend
spam_from_debian_eee at chezphil.org
Mon Sep 15 20:05:16 UTC 2008
Damyan Ivanov wrote:
> Leaving your eee unsuspended with the lid closed can be dangerous.
Well, here are some measurements:
Workload = one thread doing mjpeg decoding and another doing floating
point maths and sorting, at CPU frequency = 800 MHz or 1600 MHz as
indicated; or idle.
Ambient temp. = 19 C.
Tk = keyboard temperature, measured with a thermocouple between B, N
Tc = CPU temperature as reported by /sys/class/hwmon/hwmon0/temp1_input.
Note that the screen seems to turn itself off when the lid is closed,
irrespective of what I do in response to the ACPI event.
idle 30 49
800 MHz 30 52
1600 MHz 31 62
idle 37 52
800 MHz 39 57
1600 MHz 40 66
Lid closed, in bag
idle 44 59
800 MHz 48 66
1600 MHz 49 77
Lid closed, tape over fan vents
1600 MHz 49 79
Simply closing the lid increases the CPU temperature by at most 4 C.
Taking more extreme actions to prevent heat from escaping can raise the
CPU temperature to 17 C above normal. The maximum temperature reached
in these experiments was 11 C below the "critical" threshold set in the
fan controller (90 C). You might get closer to the critical
temperature if your ambient temperature is higher. I imagine that
reaching the critical threshold will cause some sort of automatic
shutdown, but I'm unable to prove that. My fan seems to have about 3
speeds, the highest being activated briefly when the temperature
reached 80 C and immediately bringing it down to 79 C, even with the
vents jammed up.
The label on the bottom of the Eee shows the numerous safety standards
that it meets. It would not be possible for it to get all of these
certifications if it could catch fire, or even become dangerously hot,
as a result of this sort of treatment.
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