Due to issues with some motherboards
AMD has confirmed that older chipset motherboards, based on X470, X370, B450, B350 and A320 chipsets, will lack support for PCIe 4.0, as there could be some issues with some motherboards.
Only for next-gen APUs
It appears that upcoming next-generation Ryzen processors will be limited to existing high-end and mid-range chipset while the entry-level A320 chipset will only support next-gen Ryzen APUs.
Budget oriented AM4 motherboard
MSI has shown off its newest A320M Grenade AM4 motherboard based on AMD's cheaper A320 chipset.
Crossfire works on B350 as well
According to the latest detailed specifications of the upcoming AMD socket AM4 motherboards, it appears that only the high-end X370 chipset will actually support Nvidia SLI while Crossfire will also be available on mid-range B350 chipset motherboards.
X370, B350 and A320 ready for Ryzen and Bristol Ridge
AMD has officially announced its newest socket AM4 motherboards that will be based on X370, B350 and A320 chipset and support its new Ryzen CPUs and the upcoming Bristol Ridge APUs.