I have 2x PCIe X16 and 1x PCIe 1x slots that are not being used.
Given that Linux has extensive hardware support, there are probably users with interesting PCI card usages
Aside from traditional usages like network/wireless/bluetooth/sound that can easily be used as USB (or built in advanced sound support in the MOBO), what are your use cases with PCIe?
I have a Hauppage TV tuner card that I use to get OTA TV and record certain shows. I'm pretty sure there are USB solutions, but if I remember, at the time I got this it was one of the only cards that my system supported or whatever caveat I was operating around.