Core Duo / Pentium M high pitched buzzing noise: CONFIG_HZ workaround

Almost all core duo laptops and even some Pentium M thinkpads will produce a high-pitched buzzing/whirring noise when one or more CPU's enter the C3 or C4 states. So far, the workaround has been to disable C3/C4 using the max_cstate sysfs parameter, but that results in greatly diminished battery life, especially on the Cores, whose C3/C4 states are amazingly good at conserving battery power.

Another workaround that has a very high rate of success is reducing CONFIG_HZ from 1000 (desktop default) to 100 (what our server kernel uses). It yields virtually no change in desktop performance, and often eliminates the noise while allowing both cores to reach the C3/C4 states.

Unfortunately, our only 100Hz kernel (server) does not come with restricted modules.

If we can get a separate 686-100hz kernel (the Intel Pentium M / Core lines are the only ones with this problem, to my knowledge) that comes with restricted modules, that'd make lots of Thinkpad and Core Duo owners very happy :)