Thinkpads Forum

Tonight, I just noticed that when my T61 is on battery power, there's an intermittent high-pitched noise that's REALLY LOUD. I'm going to say it's around 15KHz, because it sounds about as high-pitched as I remember CRT TVs being (back in college, one of my housemates had a TV whose 15.75KHz noise was SO LOUD it kept me up at night). It seems to correlate mostly to changes to the display, as opposed to brightness or content. Spinning mouse pointer? Noise. White screen? Silence. Black screen? Silence. Desktop just sitting there? Mostly silent, with brief burst of sound if the clock or something updates the display.

If I plug in the laptop, the sound goes away. If I remove the battery, the sound goes away.

The sound appears to becoming from somewhere near the Esc key, but I can't place it exactly.

Any ideas what might be causing this?

The noise you are hearing is probably from an inductor for the CPU power. Like the old flyback transformer on a TV that operated around 15khZ, an inductor can also make the same type of high frequency whistle. About the only things you can do is switch it out with another one, try to dampen it by encasing it with a stabilizing material (a special coil epoxy would be preferred, although people have also used hot glue or nail polish), or use the system's power manager to minimize the sound.

Any chance it's the display inverter? My X60s is making the same noise except when I have it at low or high brightness.

In between, it makes this noise. Very annoying to say the least. I'm thinking I will get a new inverter

If the sound changes pitch / loudness when you alter the display brightness, then yes, it's probably the output transformer on the inverter board.

Altering the overall level of brightness doesn't seem to affect it, though the dynamic act of changing it makes a little chirp each time I press fn-PgUp/PgDn and the brightness changes a step. Likewise, in BIOS setup, it doesn't make a peep. It ONLY makes the noise in Windows and Linux. If it were the LCD inverter, wouldn't it be making sound regardless of mode or power source?

I read a few posts about Core2duo noise due to fan-modulation, but does it REALLY adjust fan speed SO dynamically that even a keypress would cause an audible chirp from the fan?

I'm wondering whether "battery stretch" might be the culprit. Or at least the trigger. From its description, it sounds like it alters the display's refresh rate during "inactivity". That might explain why even an animated mouse pointer makes more of an impact on the noise than whether the display is all black, all gray, all white, but otherwise static & unchanging. I'm still trying to figure out how to definitively turn it off or make sure it's on.

Are there battery settings where the BIOS triumphs above the OS, regardless of what the OS might try? Or are the BIOS settings just defaults that Windows and Linux can override as they see fit?

I disabled a high pitching annoying noise from my T60 by

1. installing rmclock which is mostly used to undervolt your cpu (and/or changing cpu clock)
2. remove within this program the "c3 to c4 stepping" option
3. The noise is gone now.

The noise appears when the cpu goes from power saving c3 stepping to the more power saving c4 stepping mode.