Lee Wilbur
IT Solutions
A service of Multiverse Enterprises Inc.

The information here is provided "AS IS" and should you choose to use it, YOU DO SO AT YOUR OWN RISK.

Summary Windows does not recognize the full capacity of a large hard drive
Details If you install a hard drive larger than 128GB, Windows 2000 or XP may show the disk as 128GB instead of the actual capacity. This affects only IDE/ATA hard drives.
Cause There are two primary causes of this issue:

  1. Your computer's BIOS does not properly recognize drives larger 128GB.

  2. Your Windows installation does not have the appropriate service pack and/or registry settings.

In short, Windows or your computer's BIOS does not support Big LBA (logical block addressing) mode.

Workaround Use the drive as it is seen by the system. You will lose access to the extra space.

Purchase an external drive enclosure or similar device and make the drive an external drive.

In addition, using an additional ATA controller may be an option, as detailed below.


The solution may be a combination of the possible solutions below, depending on our system configuration.

Upgrade your Windows XP installation to Service Pack 1 or later. If using Windows 2000, upgrade your 2000 installation to Service Pack 3 or later and refer to Microsoft KB article 305098 (see related links).

Visit your motherboard (mainboard) manufacturer or computer manufacturer's web site and locate a BIOS update. (NOTE: It is up to the manufacturers to support this and if they do not, you simply may not get your computer's BIOS to recognize the full size of the drive).

Purchase an ATA PCI controller card that supports drives larger than 128 GB. The disadvantages to this are that you will need (and use) an available PCI slot for the card and it may be difficult to configure your system to boot off the larger drive (however, seeing the larger drive should not be a problem once the proper drivers are installed).

Related Links

How to Enable 48-bit Logical Block Addressing support for ATAPI disk drives in Windows XP (MS KB 303013)

48-Bit LBA Support for ATAPI Disk Drives in Windows 2000 (MS KB 305098)

Partition Types (Andries Brouwer)

Tip ID: 3Date Entered: 7/31/2005 3:29:20 PMLast Update: 8/5/2005 6:49:17 PM