Gigabyte's latest BIOS update enables PCIe 4.0 support on its AMD X470 and B450 motherboards
We know that AMD's upcoming Zen2 Ryzen 3000 CPUs will bring support for the new PCI Express (PCIe) 4.0 standard but so far, it was thought that this would also require a motherboard with the X570 chipset. Looks like that might not be entirely true as Gigabyte has rolled out BIOS updates to its X470 and B450 motherboards that enables the PCIe 4.0 option in the BIOS.
Spotted by user mVran on Reddit for the Gigabyte X470 Aorus Gaming Wi-Fi 7 motherboard, the latest F40 BIOS update adds a Gen4 option to the PCIe Slot Configuration setting in the BIOS. Users with Gigabyte B450 motherboards in the same thread have also reported that the PCIe Gen4 option along with an unlocked BCLK was available upon installing the F40 update.
While the prospect of PCIe 4.0 support for older motherboards sounds enticing, there are a few things to keep in mind here. For one, this setting will work only when a Ryzen 3000-series CPU is installed in the socket. Also, the PCIe 4.0 speeds are applicable only for lanes directly coming from the CPU — in most cases, this is the first x16 slot. The lanes coming from the chipset and M.2 slots will continue to work at PCIe 3.0 speeds.
AMD had earlier confirmed that current 300 and 400-series AM4 motherboards can support PCIe 4.0 but has left it to the motherboard vendors' discretion whether or not to implement the feature. The slot selection for Gen4 support will also depend on the board's layout and PCIe lane lengths. Any PCIe slots with PCIe 3.0 switches or extra routing will not be able to support Gen4 speeds.
The fact that users of older Ryzen motherboards stand a chance to get at least one PCIe slot upgraded to Gen4 is a quite a bonus for customers. Most motherboard OEMs have started shipping BIOS updates to offer in-place support for Ryzen 3000 chips. It remains to be seen which of these updates actually enable PCIe Gen4 support and on which motherboard models.