4
For processors that support both EIST and TM2, CPU throttling is controlled by EIST and the operating sys-
tem. The HP BIOS controls CPU throttling on TM2-only processors, resulting in support for RTPM. See
“Known Issues” on page 9 for possible compatibility issues. There is no RTPM capability for processors
that do not support EIST or TM2.
You can enable or disable the AMD Cool’n’Quiet option in the BIOS of the HP dx5150. This option is
located in F10 Setup in the
Power Management Options
section. The default Cool’n’Quiet support
for HP dx5150 systems is set to
Auto (enabled).
Operating System
Microsoft implemented EIST support in Windows XP Service Pack 2. All future Microsoft operating systems
will include EIST support.
Several Microsoft operating systems support Cool’n’Quiet, including Windows XP, Windows 2000, and
Windows ME. All future Microsoft operating systems will include Cool’n’Quiet support.
Processor Driver
Microsoft Windows controls the performance of a processor with the kernel power policy manager, a pro-
cessor driver, and the system BIOS. The kernel power policy manager sets the rules for using the correct
performance state at a given time. Once the performance state is determined, Windows uses the proces-
sor driver or system BIOS to make the changes. The processor driver changes the performance state if the
processor is not Hyper-Threaded (HT). The system BIOS changes the performance state if the processor is
HT-enabled.
The use of a processor driver, such as the generic
processr.sys
, allows Windows to interact and control
different processors - for example, Intel, AMD, and Transmeta. Vendor-specific processor drivers are also
available, such as
intelppm.sys
for Intel processors in Windows XP Service Pack 2. You can add support
for future processors, if needed.
The processor performance control policy is linked to the power management scheme. See the table in
the Power Management Scheme section for detailed information about the relationship between power
management scheme and control policy.
There are four control policies:
•
Constant -
Always runs at lowest performance state.
•
Adaptive -
CPU usage determines performance state.
•
Degrade -
Starts at lowest performance state and slowly reduces performance as battery discharges
(notebooks only).
•
None -
Always runs at highest performance state.