I got a an old dual xeon cpu mobo pc for $7. I figured I would use it for nas or worst a mid synth. It is actually a pci X. I know there was a way to convert a pci pc into a pcie computer. The pci video cards were like max 1gb ram and lacking speed too. There used to be a pci to pcie bridge in cirulation back around 2002 2003 era. I just ran across a thread today (2015) here:
https://www.gearslutz.com/board/musi...-solution.html informative on audio recording.
and here is the other way PCIE to PCI bridge:
https://www.amazon.com/PCI-Express-A.../dp/B0024CV3SA
There are many things you can do even though many so called experts say nay.