I've been doing some research on how to squeeze every little bit of performance I can for a system I intend to eventually be used only for BOINC. This system I have happens to have 16 USB ports total, 2 of which are USB 3.0, and none of these USB ports will be in use. That's a lot of potential bandwidth-to-other-processors not being used right there, and I don't like good hardware going to waste. I was wondering if maybe there was some sort of BOINC-compatible processor that could be connected through USB, or, possibly (for the USB 3.0 ports) if there was a way to connect a weak PCIe GPU?

I know there are Bitcoin USB ASIC miners, but I'm not sure if they're BOINC compatible and if so, are they even worth using? I know there are FPGAs too but I have no idea how to get into it. fpgaathome.org isn't much help.

Another idea I had was to get USB to Ethernet adapters and just do clusters with cheap ARM devices, but I have a feeling it'd be more efficient to just directly run BOINC on each of those devices individually.

I am not picky about OS compatibility or project. I prefer Linux but Windows is fine.