Western Digital claims its new 2.5- and 3-terabyte models are the highest-capacity internal SATA hard drives in the world.

on tuesday, western digital announced that it has begun shipping the world's first 3-terabyte (tb) hard drives. the company claims that these models, part of its wd caviar green family of sata drives, are the highest-capacity drives in the world.

the drives achieve this capacity through a combination of high areal density (750-gb per platter) and the use of advanced format technology, which writes 4,096 bytes per drive sector instead of the 512 bytes per sector that have been the standard for years. they're also the reason that older systems could support drives only up to 2.19 tb in capacity.

only pcs running windows vista and windows 7 will be able to take advantage of the full capacities of these drives, as windows xp does not recognize the 4,096-byte method. windows vista and windows 7 pcs, however, will not be able to boot to these drives unless they run the 64-bit versions of the operating system and are built on a motherboard that supports uefi rather than the traditional bios. (they will, however, be able to use them as a non-bootable data drive.)

the new high-capacity caviar green drives will also ship with a pci express x1 host bus adapter card that will let non-uefi systems correctly support the drives using a known driver.

in addition to their capacities, the caviar green drives also include greenpower technology, which wd claims "reduces power consumption by enabling lower operating temperatures for increased reliability and decreases acoustical noise for quiet operation."

the 3tb caviar green drives are available today for $239 list; 2.5tb versions are also available for $189 list.