Seagate Technology has identified an issue between motherboards using the Intel PIIX4 controller and certain models of Seagate hard disc drives. This issue only affects certain drive models and only motherboards utilizing the PIIX4 controller. This is an incompatibility issue and not a fault of either device.

• What chipsets are affected?
• What drive models are affected?
• How do I identify the affected drives and motherboards?
• What are the identifying symptoms?
• What is the cause of this incompatibility?
• How do I resolve this issue?

What chipsets are affected?

The following is a list of the PIIX4 chipsets known to be affected:

What drive models are affected?

The following is a list of the drive models known to be affected:

ST-31010A
ST-31011A
ST-31277A
ST-31720A
ST-31721A
ST-32120A
ST-32121A
ST-32531A
ST-33230A
ST-33240A
ST-34340A
ST-3852A

No other Seagate drives have been identified with this issue.

How do I identify the affected drives and motherboards?

Affected drives are identifiable by a chip with the following number: CL-SH7630 Compatible versions of the above models will have a green or white label stating "3.3v Compatible" on the top of the drive. Affected motherboards are identifiable by one of the following:
TX chipset motherboards have a chip labeled 82439TX (location may vary). LX chipset motherboards have a chip labeled 82371AB (location may vary). LX chipset motherboards will show a line item "PCI to Host bridge" under Control Panel, System, Device Manager, System devices.

What are the identifying symptoms?

The identified drives may exhibit one of the following symptoms when connected to a PIIX4 chipset motherboard:

• Motherboard’s BIOS will not recognize drive.
• FDISK will not recognize drive.
• FDISK will not partition drive.
• FDISK will not partition drive to full capacity, though BIOS supports full capacity.

What is the cause of this incompatibility?

The affected drives were designed for use with CMOS bus logic level input/output signals. These CMOS signals are at a logic level of 5 volts. This was done to increase the drive's immunity to noise and ringing that may exist on the AT bus.

Motherboards/host computers using the PIIX4 chipset are designed for TTL bus logic level input/output signals. These TTL signals are at a logic level of 3.3 volts. While these new motherboard/host computer chipsets may be "5V tolerant," capable of accepting input signals at a CMOS 5V logic level, their output signals can only be at a TTL 3.3V logic level. This lower output signal level from the PIIX4 chipset creates an unreliable operating condition for the affected drives.

How do I resolve this issue?

End users whose systems are experiencing the above symptoms and who have identified the proper components should call our Technical Support department for verification and further help.

Distributors with the affected models should contact their assigned field engineer or sales representative.