Some Gigabyte boards with an Xpress Recovery BIOS were apparently affected by a rather nasty capacity-reporting bug! The explanation below comes from Franc Zabkar’s HDD Capacity FAQ.

“When the drive is first in the boot order, Gigabyte’s BIOS will write a backup copy of itself to a small Host Protected Area (HPA) at the end of the user area. It then hides this image by reducing the capacity of the drive by a corresponding amount. Unfortunately a bug in the BIOS incorrectly adjusts the drive’s capacity after creating the HPA. 1TB drives are reduced to 31/32/33MB, 1.5TB become 500GB, 2TB become 1TB, and 3TB become 2TB (not 2TiB).”

This concerns the affected BIOS implementations, not every Gigabyte DualBIOS board. A big thank you to Franc Zabkar and HDAT2. Before changing HPA or capacity settings, back up what you can and check the disk layout.

Sources