Problem with high pitch noises

Information on strange high pitch, low volume noises emitted by ThinkPads.

Problem description

Even though ThinkPads are known as very silent notebooks, they tend to emit different, mostly high pitch noises in certain circumstances. The noises are of low volume and hence not realized by everyone or at least tolerated by most people. However, there are those with "bat like ears" that hear them and might be annoyed by that.

Affected Models

Noises have been experienced in the following situations:

situation	noise description	affected models
Plugged into AC / running at high CPU frequency	soft crackling, buzzing noise	T41 2379-DJU
ThinkPad suspended to RAM	constant high pitch noise	T42p
ThinkPad connected to power and switched off, with battery fully charged	constant high pitch noise	T41p 2373-GHG
moving windows or just the mouse in xorg	strange noise like a rapid series of very short high pitch noises adding to a constant kind of whistling (only as long as the movement goes)	T41p 2373-GHG
Thinkpad connected to power or working on battery, also when suspended to RAM	High pitch noise also when HD is powered down.	T23 2647-DG4 X24 2662-MWG
Thinkpad connected to power battery charged less than 60%	High pitch noise till battery is charged more than 60%.	T41p 2373-GEG
Constantly, if AC connected	High pitched, low volume constant noise.	T40 2373-88U
When the CPU freq jumps up to 1Ghz or above, or when the laptop is in suspend mode	Constant high pitched	R50 1829-6DM
(May come from harddisk.)	continuous, intermittent, low volume, high pitched	600X
ACPI puts the processor into the C3 or C4 power saving states (i.e., the system is idle).	High-pitched crackling noise.	X41 T43 2686-DGU T43p
Cpufreqd (or powernowd etc.) slows down the processor, for exemple at the end of an heavy task.	High-pitched crackling noise.	T42
When on battery	Almost inaudible screeching sound, or sometimes beeping (when wifi is on)	R52 1858-A11
CPU is used much AND laptop is on AC power AND the TFT panel is enabled.	Screetching high pitch noise, like a million crickets	X41

Affected Operating Systems

All, though Linux appears especially susceptible.

Possible sources

• CPU activity: On some models the noise is triggered by certain CPU power states or activity patterns (as proven here).
• Graphics processor: In some models from the T2x era, e.g. the T23, the problem was related to the graphics circuitry and occured especially or only while making use of DirectDraw functions. IBM was able to fix it through a BIOS upgrade.
• Hard disk: On some ThinkPads the processor and hard disk are adjacent and produce similar noise. For example, in the X41 the sound generated by the hard disk is likely to be loudest at the vent.

Status

The problem is highly specific to operating system, model and even individual machines. There is no universal solution, but on most machines one of the following will reduce or eliminate the noise (possibly at some cost in power consumption).

Solutions for CPU-triggered noise

Change the timer interrupt frequency

Change the "HZ" kernel constants to alter the frequency of timer interrupts. Discussion:

• Andreas Karnahl: i've read in several forums it has something to do with the "idle"-state (or "C3") of the processor. There is a frequency called "timer interrupt" (or something like that). Since kernel 2.6x it is set to 1000 Hz by default (compared to 100 Hz in Kernel 2.4x). The exact reason i don't know, but it is safe to change this frequency to 100 Hz in kernel 2.6x (by the way, windows up to XP uses 100 Hz by default).
  Just do the following:
  

In [path to kernel-sources]/include/asm-i386/param.h find the line

#define HZ 1000

and change the value of HZ to 100:

#define HZ 100

Then recompile the kernel.
After i changed it on my ThinkPad A30 (under SuSE 9.2 and 9.3) and recompiling the kernel the high pitch noise is gone away.

• Omar Yasin: Worked on my R52, thanks.

• Thinker: In modern kernels this constant is in the kernel configuration (Processor type and features -> Timer frequency).

Limit ACPI CPU power states

Prevent the CPU from going into high ACPI power saving states. Discussion:

• Stefan Baums: I raised this issue on the linux-kernel mailing list, and from there it was forwarded to the acpi-devel mailing list. See the discussion here and here. Results: The idle=halt kernel parameter disables ACPI C-state switching entirely (i.e., locks the processor in C1). It is preferable to pass to the ACPI processor component the option max_cstate=2, which only disables the problematic states C3 and C4. The only way to accomplish this that worked for me was to compile the ACPI processor component permanently into the kernel (CONFIG_ACPI_PROCESSOR=y) and then enable it by adding the parameter processor.max_cstate=2 to the boot command line (and of course removing idle=halt). Now the computer switches back and forth between C1 and C2, but avoids the noise-inducing C3 and C4, and frequency scaling works regardless. (X41)
• Simon Eggert: The processor.max_cstate=3 option worked for me on my T43p thanks.
• Adding options processor max_cstate=2 in /etc/modprobe.conf (or /etc/modprobe.conf.local on my SuSE 9.3 installation) prevents the CPU permanently from entering into C3 and higher states. (X40, R52)
• Thinker: On one T43, this worked even with processor.max_cstate=3. That is, C3 was silent and only C4 produced whining (at both HZ=100 and HZ=250).
• Thinker: These options affect power consumption when the CPU is idle. Here are the figures on one ThinkPad T43:
  • processor.max_cstate=4: 15160mW (default, noisy)
  • processor.max_cstate=3: 15770mW (660mW higher, silent)
  • processor.max_cstate=2: 16100mW (2940mW higher, silent)

Disable ACPI CPU power states

Completely disable CPU ACPI power states. Discussion:

• From Martin Steigerwald: I made the observation that I get at least less high pitch noises on my T23 when I do not use the two ACPI modules "processor" and "thermal" (depends on the first one). I have no clue, why. Anyone with similar experiences?

Omar Yasin: I've got a R52 and when I load the same ACPIO modules the high pitch noises are not as loud but I can still hear them.

• Niko Ehrenfeuchter: I'm experiencing the same here on my X24. Removing the "processor" module also stops the pitch noise, which does ONLY occur when setting the CPU to maximum speed (using cpufreq). On low speed it's completely silent, even having loaded the processor module.

• Rolf Adelsberger: I can confirm this: the high pitch noise is only remarkable (at least with my ears ;-) ) if the processor speed is set to maximum frequency.

• Stefan Baums: My X41 produced a high-pitched crackle from the processor vent on the left. Changing HZ did nothing, and the 'processor' module could not easily be removed from the system (Ubuntu 5.04). What solved the problem for me was adding idle=halt to the boot command line. Unfortunately, this solution only lasts until the first hibernation or suspend - when the computer (X41) resumes, the high-pitched crackle is back.

• The idle=halt solution combined with setting #define HZ 100 in the kernel fixes the problem on a T43.

• jhatch: idle=halt plus #define HZ 100 also worked on my T43. It still reverts back to noisy after a suspend/resume though. This needs to be fixed...

Prevent idling

Indirectly avoid power saving states by making sure the CPU is rarely idle:

• Paul RIVIER: Here is a really simple workaround. C3 / C4 states are mainly called when the cpu freq is higher than required, for example if your cpufreqd is lazy to slow down the frequency but quick to raise it. That is why I use powernowd with the builtin "passive" mode, which is lazy for raising frequency, but quick to go back to the lowest. Now I don't hear them as often as before, as I avoid C3/C4 states at high frequency.

• The problem also occurs on my X41 with 2.6.11. Setting up frequency scaling with the ondemand governor makes things a lot better, as the processor does not stay with the maximum frequency when in idle mode. It can be still heard sometimes, though.

• On a T43 the noise was gone after dropping cpufreqd and switching to the ondemand governor - maybe because of the high sampling rate? (used the default: 10ms)

Other solutions

Disable UltraBay

• Naheed Vora: My T41 (2373-268) started to give high pitch noise ocassionally, when I upgraded to 2.6.11 kernel. I tried to unload lot of modules but finally figured out that disabling bay stops the noise. If you have ibm-acpi, do (need a cleaner solution): $ echo eject >/proc/acpi/ibm/bay .

Disable IrDA

• Mike Perry: I was able to cure an intermittent high-pitched whine on both my X24 and X40 by disabling the Infrared port.

Disable the Linuxant Modem Driver

• Joern Heissler: I made another experience. I played around with linuxant conexant modem drivers. After loading them I got some noise on my T42p.