As for motherboard i would go with the msi B450 Tomahawk or the msi B450-a pro but all msi b450 boards have the bios button.
Easy to flash the motherboards without cpus.


I already have a Ryzen 1700, I mined a lot of XMR in the past and I pay the CPU with it
It's very tempting to change for a Ryzen 9 3900, it's a monster, but I don't know if I'll do because electricity in my country is very expensive at the moment and probably will not worth, but as an old miner, it's tempting me everytime
