Are UAD-2 cards supported on PCIe x4 or x16 slots?

Yes, a x1 card should work in a x16 slot It's good that you've got it to work in a x1 slot What else have you tried it in besides the x16 slot

PCIe x1 x4 cards in x16 slot ✓Click here to subscribe to my YouTube channel: https:

pcle x16 slot The 'x16′ indicates the maximum number of PCI Express lanes supported and thus, the length of the slot As version , each lane provides

pcle slot PCIe SSD Performance; EZ-Latch：PCIe x16 Slot & Connectors with Quick Release & Screwless Design; Fast Networks： LAN & Wi-Fi 6E