The high frequency noise of t40,t41

[yxr7730]

Hello,
I am a new member here,and I am very glad to join you.

I just want to buy a second hand t40 or t41,but the high requency noise of the lcd or the mainboard make me mad(I have used t43 for a week).Some one tell me it appear when someone moving the mouse or a program useing the direct.

My qustion is :
can I fix it by refreshing the BIOS?
If not ,t40 ,t41 or Xxx,the noise of witch one is smaller?

[christopher_wolf]

Welcome to the Thinkpad Forums

The high frequency noise you describe occurs, to different extents and different times, on all Intel P-M based laptops (including the T43 all the way back to the T40). There are several soultions for getting rid of it that most users report success with. One is to toggle the power scheme settings or to plug the system into AC, then pull it out and run on battery power. I have only heard the buzzing rarely and toggling the power schemes worked everytime; I haven't heard it for almost half a year now.

[Thinkpaddict]

I have a T41p, and I don't notice the high frequency pitch that you refer too. If it is there, it is surely faint enough that I can't hear it.

I know the high pitch you are referring to. I have experienced it in two different T23s, but to different degrees. It apparently comes from the LCD inverter, and the noise's intensity (and pitch) vary according to the LCD backlight intensity. One of the T23 computers had this problem much more apparent than the other one, which leads me to believe that you shouldn't rely on a specific model as a guideline to predict the intensity of the noise. The best bet would be to be able to try the computer before buying it (if this is an option which you have at hand). If you can't afford to do this, it is going to be a crap shoot.

Also, be aware that this is an issue (I doubted whether I should call this an issue, but since it bothers you so much it is obviously an issue to you) that is not specific to Thinkpads, but to laptops in general.

Good luck!

Edit: My X24 (which I am typing at right now) doesn't have that issue at all.

[yxr7730]

Welcome to the Thinkpad Forums

The high frequency noise you describe occurs, to different extents and different times, on all Intel P-M based laptops (including the T43 all the way back to the T40). There are several soultions for getting rid of it that most users report success with. One is to toggle the power scheme settings or to plug the system into AC, then pull it out and run on battery power. I have only heard the buzzing rarely and toggling the power schemes worked everytime; I haven't heard it for almost half a year now.

Thanks for you answer .
How can I set the power scheme settings ?

[christopher_wolf]

Either with the Power Manager or through the Power *.cpl in the Windows Control Panel.

[raabjerg]

A more sustainable solution might be to disable power management on all USB root hubs (device manager -> properties for all USB root hubs -> power management)

I know this does not work for all users, and some people say it uses slightly more power, but it has worked for me, and the annoying buzz is gone (when not running flash-enabled websites)

[silverfast]

My 3 cents about the noise you asked about: i don't hear it on my T40 at all, whatever the power scheme used. I do hear it on the T23 though and it seems to be related with the LCD brightness set. There is always some noise when i set to to anything lower than max but once it's full brightness the noise is gone.

Another thing causing a specific high pitch sound is... memory modules or at least something that has to do with them. When i hear the annoying sound, i just shutdown the machine and refit SO-DIMMs and the noise is gone for sometime... never found out why would it work but it does for me. Any ideas?

[Thinkpaddict]

My 3 cents about the noise you asked about: i don't hear it on my T40 at all, whatever the power scheme used. I do hear it on the T23 though and it seems to be related with the LCD brightness set. There is always some noise when i set to to anything lower than max but once it's full brightness the noise is gone.

Another thing causing a specific high pitch sound is... memory modules or at least something that has to do with them. When i hear the annoying sound, i just shutdown the machine and refit SO-DIMMs and the noise is gone for sometime... never found out why would it work but it does for me. Any ideas?

Well, everytime there's noise there's movement (or vibration).

The LCD brightness causing noise is due to the fact that when you reduce brightness this is done by engaging a circuit in which there seem to be some coils that vibrate at high frequency (but not high enough to be inaudible to most human ears). Depending on how the coils themselves are setup physically against the housing, or due to other physical factors, the noise is more prominent in some computers than in others.

As to the RAM modules causing that, I suppose it could be a similar issue related to the memory bus frequency, although I find it a little hard to believe that it would actually cause enough movement to make it do a noise.