MSI is among the motherboard manufacturers who had to significantly modify their UEFI firmware packages to cram in AGESA ComboAM4 1.0.0.3ab microcode on their AMD 300-series and 400-series chipset motherboards, due to firmware ROM size limitations. Most older MSI AM4 motherboards have 128 Mbit (16 MB) SPI flash ROM chips, which proved insufficient to integrate the latest AGESA microcode alongside its feature-rich ClickBIOS 5 UEFI setup program. MSI addressed the issue on two fronts. For its existing motherboards that have 128 Mb flash chips, it released BIOS updates that have AGESA 1.0.0.3ab, but shed some bulk on the setup program, by replacing ClickBIOS 5 with the "GSE-lite" setup program. The company is also releasing newer revisions of many of its AMD B450 chipset motherboards anticipating demand from the section of 3rd gen Ryzen buyers who don't want to spend at least $170 on an AMD X570 motherboard.

These revised motherboards feature "MAX" in the name, and come with 256 Mb (32-megabyte) SPI flash ROM chips, enabling MSI to combine AGESA ComboAM4 1.0.0.3ab with ClickBIOS 5, and not compromising on any of the motherboard's BIOS-level feature-set. These motherboards also come with out-of-the-box support for all of the 3rd generation Ryzen processors launched so far, as indicated on the box. The boards also retain support for A-series "Bristol Ridge" and "Raven Ridge" Athlon APUs that had faced the axe with the latest BIOS updates. The B450 Tomahawk MAX and Mortar MAX are characterized by matte-black heatsinks replacing silver; while the B450-A PRO MAX has the "MAX" logo clearly printed on the VRM heatsink. Pricing of these boards are expected to be on par with the models they're replacing.