In the interest of helping others who may be building X5000 systems, here are three cards I've tried recently ...
This RTL8139 PCI Network card DOES NOT work:
https://www.amazon.com/gp/product/B0117 ... UTF8&psc=1
This RTL8169 PCI Network card DOES work:
https://www.amazon.com/gp/product/B008U ... UTF8&psc=1
This RTL8169 PCI-E Network card DOES work:
https://www.amazon.com/gp/product/B003C ... UTF8&psc=1
This PCI-E Sound card DOES NOT work:
https://www.amazon.com/gp/product/B01MT ... UTF8&psc=1
I'm interested in identifying WORKING sata cards (preferrably PCI_E) -- any suggestions?
Edit: Modified my recommendation based on this thread: viewtopic.php?f=57&t=3625&start=10
The sound card is a rev 1 and I HAVE had issues with it.
Edit 2: Added a working PCI-E network card.