Problem with high power drain in ACPI sleep

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Information about the problem of too high power drain in ACPI sleep mode.

Problem description

Several people realised that their ThinkPads eat up too much power while suspended to ram via ACPI. Compared to APM suspend to ram the power drain is experienced to be about 10 times as high, 2-5 Watts. This empties the battery within one or two days.

Affected Models

  • Different symptoms have been reported for different models. In some models the origin of the power drain is obvious (backlight on during suspend), in other models there is no obvious reason.
  • On some models/configurations the higher power drain couldn't even be realized or was at least significantly lower.
  • The T4x thinkpad series (T40, T40p, T41, T41p, T42, T42p) suspends to ram just fine, and there are no components that are obviously left powered up. The ultrabay and network light is on, but that is the same under windows. Nevertheless, the following models suffer from the mysterious power drain:
T41 2379-DJU
T41 2373-9HU
T40 2373-MU3
T40 2373-92U
T40p 2373-G1U
T40p 2373-G3U

In contrast, the following models work (no heightened power drain):

T41p 2373-GKG
TP41p 2373-GGG

Affected Operating Systems

  • Linux, all flavours.
  • Windows, for some models as well (only when using non-IBM drivers).

Status

The cause of the problem is not really clear, yet. A faulty DSDT might be responsible for the phenomena. The thinkpad T4x DSDT has a few small bugs, none of which should cause the extra power drain.

There is a interesting discussion taking place in the OSDL Bugzilla.

Solutions

None so far.

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