I have searched in the forums but I did not find any post related to this topic, We encourage you to initiate your project and post your results or errors found during the process, my advice before you start is first verify the PCIe (card and Galileo) compatibility also if it has drivers for Linux.
Hi. USB 3.0 requires the use of PCI Express slots operating @ 5 GT/s (ie. Gen2 speeds), not Gen1 speed. As was confirmed earlier:
the mini-PCIe interface is operating at 2.5 GT/s so very unlikely you will achieve USB 3.0 speeds.