Biostar BIOSes enabling PCIe Gen 4 on AMD 400-series Motherboards are available
Taiwanese computer giant Biostar has released BIOS updates for several 400 series motherboards which enables fourth generation PCI Express on the first x16 slow as well as the M.2 NVMe slot if a Ryzen 3000 CPU is used.
Biostar representatives showcasing their product line-up at Comptex Tappei in June 2018.
The Biostar motherboards with BIOS updates enabling PCIe 4 available are:
- AB45C-M4S (B450MH)
- AB35G-M4S (B45M2)
- AX47A-A4T (X470GT8)
- AX47A-I4S (X470GTN).
The BIOS updates can be acquired from their support download page. They are marked as "AGESA ComboAM4 PI126.96.36.199 PatchAB ".
Only the topmost (primary) PCI Express x16 slot and the NVMe slot will have PCIe 4 if a Ryzen 3000 CPU is present. The PCIe slots which go through the chipset will still be limited to PCIe 2
AMD does not officially support PCIe 4 on 400 series motherboards. Hardware manufacturers like Biostar and ASUS are able to enable it nevertheless by changing the binary AGESA blobs from AMD which they embed into their BIOS images.
Machines using the newly released Biostar BOISes will not have a functioning RDRAND instruction. RDRAND was plain broken on Ryzen 3000 series CPUs at launch. AMD admitted it's broken and promised a BIOS update after pretending there was no problem for days. They then released a AGESA BIOS microcode update which caused all kinds of stability issues causing it to promptly be pulled. This is why these new Biostar BIOS updates will fail to boot most modern Linux distributions - with Debian being a notable exception. This; this is great news if you have one of the above mentioned Biostar motherboards and a Ryzen 3000 series CPU and you like Debian.
published 2019-07-22 - last edited 2019-07-30