Gigabyte has released its new F40 bios for the X370 K7 that enables PCIe Gen 4.0. Other boards should receive similar support soon. It is very important that you follow the instructions for upgrading the bios. I did this with a USB stick and directly within the bios. First you need to install EC FW Update Tool (B19.0517.1 or later version) to avoid 4DIMM DDR compatibility on 3rd Gen AMD Ryzen CPU. This is found within the Utility section of your Gigabyte motherboard's support page. This will reset your bios version to F2 after rebooting if I remember right. It is okay and don't freak out! Next you need to update to bios version F31 from the link above. Then you can subsequently update to bios version F40. Thus you need to have both bios versions unzipped on the USB stick. Robert Hallock from AMD said this about older motherboards getting upgrades to PCIe 4.0. AMD doesn't officially support it. Free is free so YMMV. At any rate you're going to want to upgrade the bios for 3rd gen Ryzen processors. It does get rid of support for Bristol Ridge processors as the physical space on the bios is too small to support everything. Stay [H]ard and [H]ave fun!