View source for Talk:Problem with high pitch noises

==Discussion of "Limit ACPI CPU power states"==

*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 [http://sourceforge.net/mailarchive/forum.php?thread_id=7593600&forum_id=6102 here] and [http://sourceforge.net/mailarchive/forum.php?thread_id=7599419&forum_id=6102 here]. Results: The <code>idle=halt</code> 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 {{bootparm|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 (<tt>CONFIG_ACPI_PROCESSOR=y</tt>) and then enable it by adding the parameter {{bootparm|processor.max_cstate|2}} to the boot command line (and of course removing {{bootparm|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 {{bootparm|processor.max_cstate|3}} option worked for me on my {{T43p}} thanks.
* Adding <code>options processor max_cstate=2</code> in {{path|/etc/modprobe.conf}} (or {{path|/etc/modprobe.conf.local}} on my SuSE 9.3 installation) prevents the CPU permanently from entering into C3 and higher states. ({{X40}}, {{R52}})
* [[User:Thinker|Thinker]]: On one {{T43}}, this worked even with {{bootparm|processor.max_cstate|3}}. That is, C3 was silent and only C4 produced whining (at both HZ=100 and HZ=250). 
* [[User:Thinker|Thinker]]: These options affect power consumption when the CPU is idle. Here are the figures on one ThinkPad T43:
** {{bootparm|processor.max_cstate|4}}: 15160mW (default, noisy)
** {{bootparm|processor.max_cstate|3}}: 15770mW (660mW higher, silent)
** {{bootparm|processor.max_cstate|2}}: 16100mW (2940mW higher, silent)

== Harddisk related noise ==

on my T43p the noise definitely comes from the harddisk and can be heard both in Windows and Linux. Only at boot time, before the harddisk spins up, or when I manually spin down the harddisk with

{{cmdroot|hdparm -y /dev/sda}}

the system is silent.