Unfortunately, the Thunderbolt card we make only works as a target device. While it has a PCIe card edge connection it is a slightly custom pin-out and the device on the card is set in downstream mode. The Thunderbolt spec makes it difficult and costly to make a Thunderbolt certified host card. Many parameters of Thunderbolt are tied directly to motherboard resources that are not part of the PCIe slot. These include the requirement for Thunderbolt to support Display Port video and hot-swap of the cable through BIOS.