A picture, supposedly an official Asus image, has been circulating in recent days indicating that several B450 and X470 boards support PCI-Express 4.0. In light of this, AMD again clarified that the final AGESA for B450 and X470, which are compatible with Ryzen 3000, do not support PCI-E 4.0, meaning that if the motherboard supports PCI-E 4.0, it does not have the current AGESA.
AMD clarifies again that it will not support PCI-E 4.0 in B450 and X470
Our plan is unchanged. For the reliability and consistency reasons cited at Computex, we still intend to disable PCIe Gen 4 for pre-X570 motherboards. That AGESA is being released to motherboard manufacturers soon.
As we have already seen, the previous AGESAs have several problems, so it is not recommended to use them. Apart from the problem of the boost, which is the best known, the previous AGESA have memory errors, problems with WHEA errors (which are still present in the last AGESA), and compatibility errors with certain applications and even with several Linux distributions.
“In daily use, PCI-E 4.0 has no advantages, not even for SSDs, let alone GPUs, so it is not worth using an old AGESA to have this technology. We recommend not to install these bios, which are not only available in Asus, but also in other brands.”