The USB3HDCAP only works with USB 3.0 (or later) ports, because the USB3HDCAP requires more bandwidth than USB 2.0 (or earlier) ports can provide to transfer data to the computer system. If you use a USB 2.0 or older port with the USB3HDCAP, the USB3HDCAP will be detected in Device Manager, but will not display video in StreamCatcher. StreamCatcher will show No Signal and a video frame rate.
If you need to purchase a USB 3.0 card for your system, refer to the USB 3.0 Cards section on the StarTech.com website: http://www.startech.com/Cards-Adapters/USB-3.0/Cards/.
Note: Refer to the following FAQ to make sure that you purchase a compatible chipset card for your system: https://www.startech.com/faq/USB3HDCAP_Chipset_Incompatibilities.