Thintel
ICH8 docs, section 5.13.5.1:
To eliminate the audible noise caused by aggressive voltage ramps when exiting C4 states at a regular, periodic frequency, the ICH8 supports a method to slow down the
voltage ramp at the processor VR for certain break events.
Sounds good. Section 9.8.1.6:
C4_TIMING_CNT: Bit 6 Slow-C4 Exit Enable —When 1, this bit enables the Slow-C4 Exit functionality.
Well, hey, we can quirk this on and make life better for everyone oh wait section 9.8.1.4:
Bit 0 C-STATE_CONFIG_LOCK: When set to 1, this bit locks down the C-State configuration parameters. The following configuration bits become read-only when this bit is set:
...
The entire C4 Timing Control Register (C4_TIMING_CNT)
Thanks, Intel. Thintel.