While AMD is continuing support for the AM4 platform with its 3rd Gen Ryzen processors, backwards compatibility may not extend to all 300-series motherboards. Reports emerging from AMD’s post-announcement press gathering suggest BIOS chip limitations could be the determining factor in whether your board can support 3000-series Ryzen processors or not.

AMD’s AM4 platform is set to stick around around until next year, 2020. Until that day arrives, AMD has promised that all of its desktop Ryzen chips will be physically compatible with the current PGA AM4 socket and accompanying chipsets. For the most part, forgetting Threadripper for a moment, AMD has stuck to its word, too. Although support for 3000-series chips may now come down to a question of 16MiBytes.

The BIOS chips on AM4 motherboards are only smol, and this could constrain the amount of CPU microcode vendors are able to store all at once. While 400-series motherboards are able to store a roomy 32MiBytes, enough for all three generations of Ryzen’s code, the older 300-series boards are stuck at 16MiBytes.

A report from PCGamesHardware indicates that vendors may have to decide on whether they wish to hold off on 3000-series CPU support or risk cutting microcode for past generations and fork BIOS support for each 300-series motherboard. That’s a tricky needle to thread, and the latter could come back to bite their customer support in the ass.

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At least 400-series boards appear to be raring to go for the 3rd Gen Ryzen processors, and vendors should be rolling out BIOS updates later in the year that offer support for the latest processors. AMD has also confirmed that it’s possible to offer PCIe 4.0 support for the primary x16 slot on these motherboards, pending vendor support.

AMD will also be rolling out ‘AMD Ryzen Desktop 3000 Ready’ stickers to indicate new motherboards that have been pre-loaded with 3rd Gen Ryzen friendly BIOS firmware.

AMD’s 3rd Gen Ryzen processors were announced over at CES, promising Intel-breaking performance and power efficiency. AMD plans to launch the chips sometime mid-2019, and we suspect that will fall right around Computex in May/June.