Hello.
I own Gigabyte X470 Gaming 7 and I saw the news that AMD will not officaly support Zen 3 cpus on 400 and 300 series boards but they did it also for B350 and some X370 when Zen 2 launched so support was up to manufacturer. I payed 240bucks for this board with AMD promise to support it until 2020. I need to know how much my bios have If I have 32Mb I still have chance with 16 Im probably done for. 
Edit: I found it, its 16
Greetings,
Not completely clear what your question is? I guess whether your board will support Zen3? The board is manufactured by Gigabyte, AMD does not bear any responsibility to support it for any length of time, now or ever.
You are correct about your BIOS. Chips are 128Mbits = 16 Megabytes
Zen3 support. I'd say there is a chance because the current Ryzen 9 is already based on 7nm tech. Hope these are the questions you were hoping to get answers for.
