JSI Tip 6412. How do I adjust the elapsed time before Windows XP places my processor in a deeper idle state?

If you experience intermittent errors in Windows XP, it may be the result of when Windows dynamically adjusts the processor power state to a deeper idle state (from the C2 state to the C3 state).

NOTE: See Windows XP SP1 intermittently reports an I/O device error when you access your floppy disk?

The steps in this tip will increase the elapsed time from 100,000 microseconds to 500,000 microseconds in Windows XP SP1 (or greater), but your hardware may require a different value, so contact the computer manufacturer:

1. Use the Registry Editor to navigate to:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folders\PowerCfg\ProcessorPolicies\0.

2. Double-click the Policies Value Name to open the Edit Binary Value dialog.

3. Change the first four bytes at 0030 from A0 86 01 00 to 20 A1 07 00, so that the line is displayed as 20 A1 07 00 28 3C 00 00.

4. Change the last four bytes at 0078 from A0 86 01 00 to 20 A1 07 00, so that the line is displayed as A0 86 01 00 20 A1 07 00.

5. Repeat steps 2 - 4 for the following keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folders\PowerCfg\ProcessorPolicies\1
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folders\PowerCfg\ProcessorPolicies\2
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folders\PowerCfg\ProcessorPolicies\3
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folders\PowerCfg\ProcessorPolicies\4
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folders\PowerCfg\ProcessorPolicies\5

NOTE: If your processor supports performance control and C-states, these settings apply to all power schemes.

NOTE: A0 86 01 00 and 20 A1 07 00 are stored in reverse order and are really 0x0186a0 (100,000 microseconds) and 0x07a120 (500,000 microseconds) respectively.

NOTE: See http://msdn.microsoft.com/library/en-us/power/base/processor_power_policy_str.asp

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