Both Seagate and WD have announced 3 TB external drives, and now WD has broken new ground with a 3TB internal hard drive. The WD Caviar Green 2.5 and 3 TB hard drives are bundled with an Advanced Host Controller Interface (AHCI)-compliant Host Bus Adapter (HBA) that allows both 64-bit Windows 7 and Mac OS X Snow Leopard, along with 32-bit Vista and Windows 7 platforms to make full use of the new drives.

Because of limitations to 32-bit Windows operating systems and motherboards in many computers, drives bigger than 2.19 TB can't be fully utilized. The Advanced Host Controller Interface adapter solves this issue by enabling the operating system to use a known driver with correct support for large capacity drives.

The 3.5-inch, 750 GB-per-platter areal density drives also promise low power consumption, lower operating temperatures and quiet operation.

The 3 TB WD Caviar Green SATA hard drive is priced at US$239. The 2.5 TB version costs US$189.