I've seen a number of PCIe USB cards fail to work with our servers. I'm not sure specifically why, but I can tell you that there aren't any validated ones. The best recommendation I could make to you would be to make sure that the firmware is all up to date, but I'd still suggest tempering your expectations with that card.
I tried installing a U3N2-D low-profile USB 3.0 PCIe card in two FC630 servers, but the card seems to be unrecognized. I'm running Red Hat Linux and when I do an lspci I can see plenty of PCIe bridges including the X710 mezzanine card and the RAID controller that connects to the FD332, but I can't see the USB PCIe card. I think I noticed some link training errors during boot. Is this card just incompatible for some reason or is there something else possibly wrong?
PCIe USB card in FC630