ASUS sparked a fire in the motherboard market this week by listing its older X470 motherboards which are compatible with PCIe 4.0. This came in contrary to the initial claims made by AMD over the compatibility of PCIe 4.0 with X470/370 boards.
AMD earlier made claims that the older boards will not receive PCIe 4.0 support due to lack of stability. The company backed the statement by claiming that the boards are incapable of running PCIe 4.0 signaling, coupled with the requisite stability and performance.
It turns out that AMD is sticking to its original assertion, and the PCIe 4.0 options seen in the older board BIOS versions will be disabled in the final versions. The decision will provide streamlined experience and reduce confusion among the consumers. The users who still want PCIe 4.0 despite the AMD BIOS block, can use the beta versions of the BIOS, although, AMD will not guarantee the stability and performance uplifts.
In hindsight, users will lose support for PCIe 4.0 if they upgrade to a fresher firmware but will benefit from the AMD updates that boost performance. GPUs in 2019 are yet to harness the full capability of the new slots, but if you want the new PCIe 4.0 anyway, opt for the newer X570 motherboards.