I run a twitch.tv livestream channel and built a new Ryzen 7 1800X based computer using the the X370 XPOWER Gaming Titanium. I found that currently there are issues with different capture cards used to capture footage of PS4 and other game console footage.
Avermedia Live Gamer HD (C985) - The X370 XPOWER Gaming Titanium does not post when this pcie x1 device is installed in any of the pcie x1 slots as well as the pcie x4 slot. LED debug code 96 - PCI Bus Assign Resources then followed by 97 - [Console Output devices connect] eventually hanging at code A2 - [IDE Detect].
Elgato HD60 Pro - The X370 XPOWER Gaming Titanium is able to post but does not recognize the card in windows. Therefore the card is unusable. There is a reddit thread regarding this very issue.
Avermedia HD PVR / Dark Crystal Pro (C027) - This is an older PCIe based capture card that does work with the AM4 motherboard, however, after resuming the PC from sleep, this card will cause a bugcheck event in Win 10 resulting in a BSOD. It is intermittent but has been duplicated several times.
Windows Event Viewer details on the BSOD: The computer has rebooted from a bugcheck. The bugcheck was: 0x0000009f (0x0000000000000003, 0xffffbc0a899c9580, 0xfffff803dcf4f960, 0xffffbc0a8f3ac010). Removing the PCIe x1 capture card from the system resolves this issue.
All three of these cards have been used in older AM3+ and Z87 based motherboards for more than 3 years so the issue is definitely fixable via microcode update (UEFI update). This needs to be high severity on the fix list since it has potential to affect a large target market for the AM4 platform.
I can report as a workaround, using a USB 3.0 or 3.1 based external capture device such as the Elgato HD60s does work so the issue seems like bad IRQ allocation and sharing on the chipset's uplink to the infinity fabric or something along the lines of how the microcode is identifying these PCIe devices based on initialization and detection.