[ltp] T41 high-pitched noise

[Frederik Wagner]

On Fri, 7 May 2004 11:15:13 +0200 (MEST)
Frederik Wagner <frederik.wagner@hmi.de> wrote:

> I bought a Thinkpad T41 with preinstalled WinXP.
> After installing Debian linux I noticed a high pitched noise which is 
> best audible over keyboard. It only occurs when the AC in plugged in, on 
> battery there is no noise.
> Under WinXP there is no noise, neither on AC nor battery.
> Could it have something to do with the power management under linux?

I found out some more details about the high pitched noise I was asking about:

1. It only occurs when ac is plugged in.

2. Under linux there is a continious hight pitched noise, when the frequency of the processor is about larger then 1GHz (I have an 1.6GHz Pentium M)... When the speed is lower it's not audible (I'm using the powernowd which works great with apm). It's not audible as well when under full speed _and_ full cpu usage...

3. When the battery is nearly full (or the battery is taken out and ac plugged in) there is a whistling (like static noise) correlated with acces to the harddisk, but not at the hard disk but in the back where the connection to the ac is over the keyboard. This is a different sound I was describing before...

4. The sound under 3 occurs even under WinXP. I didn't realy check if it is audible when the battery is not nearly fully charged (either XP/Linux).

Does anyone of you noticed these things or has an explanation? Probably it is a voltage transformer or something like that...
I hope anyone can tell me something an I hope my laptop is not somehow faulty. In the beginning the CD drive was not working so I already some trouble... But at least the IBM customer service is very good... But I don't want to "bother" them again :-/

TIA and bye,
	Frederik!