Since Thunderbolt is simply a low-level PCIe interconnect, the onboard ASMedia SATA controller OPROM was recognized and loaded during POST. We also had the option of booting off the drives in the BIOS.

IMG 1625 WD My Book Thunderbolt Duo 6TB and ASUS ThunderboltEX: High Speed Mass Storage on Windows

bootover WD My Book Thunderbolt Duo 6TB and ASUS ThunderboltEX: High Speed Mass Storage on Windows

Some performance tests… things looked up to spec and definitely adequate for the product's target audience of digital media professionals.

anvil WD My Book Thunderbolt Duo 6TB and ASUS ThunderboltEX: High Speed Mass Storage on Windows

blackmagic WD My Book Thunderbolt Duo 6TB and ASUS ThunderboltEX: High Speed Mass Storage on Windows

aja WD My Book Thunderbolt Duo 6TB and ASUS ThunderboltEX: High Speed Mass Storage on Windows

The WD My Book Thunderbolt Duo can be found on NewEgg at US$599 for the 4TB version and US$699 for the 6TB version. Comparatively speaking, the Thunderbolt-less My Book Studio II which has quad-interfaces (FireWire 400/800,USB 2.0, eSATA) and the same hard drives retails at almost US$200 less, which goes to prove the proverbial early adopter tax.