PRB: Memory Corruption or PC Hangs Entering C3 CPU Power State

• Microsoft Windows 98

SYMPTOMS

If the power management settings are configured to allow the processor (CPU) to enter the C3 power state on a computer supporting the Advanced Configuration and Power Interface (ACPI) specification, one or more of the following symptoms might occur:

• Memory is corrupted after several minutes of inactivity.



• The computer stops responding (hangs) after several minutes of inactivity.

CAUSE

If the motherboard uses the Intel 440BX chip set, memory might be corrupted when the CPU enters or leaves the C3 state. This occurs because of a problem with the Intel 440BX chip set when entering and leaving the C3 state.

If it uses the Intel PIIX4-E IDE controller chip set, the computer might hang. This might occur if a bus mastering operation occurs while in the C3 state.

RESOLUTION

You can work around this issue by preventing the CPU from entering the C3 power state.

To do this, set the "lvl3_latency" value in the (FADT) to a value greater than 0x3E8 (1000 decimal) in the computer's BIOS. If lvl3_latency is greater than 0x3E8, the Windows 98 ACPI driver does not enter the C3 state.

The recommended value for lvl3_latency to work around this issue is (0xA000 + lvl3_latency), where lvl3_latency is the C3 latency value that would otherwise be used.

STATUS

Microsoft has confirmed this to be a problem in Windows 98.

Additional query words:

Keywords          : kbenv kbhw win98 kbWinOS98 
Version           : WINDOWS:
Platform          : WINDOWS 
Issue type        : kbprb 

Last Reviewed: May 7, 1999