Why does it take that long to post? I've had multiple Ryzen 300-series motherboards, none of them take anywhere near that long to boot outside of using something like some server-grade HBA that has its own boot step.

I have no idea, but it's a known issue, memory training maybe? It's a gaming PC so nothing special going on, ROG HERO motherboard, 32GB DDR4 (4x8GB), GTX 1080Ti.

I haven't used it much in recent years, I built it for gaming but had kids a couple of years later, now I game on whatever is convenient in the small burts I get; which is also the reason I haven't bothered upgrading it.

You'll love ddr5 times.

Sarcastically, or seriously? Is the issue due to memory? Training or something?

Training, till you get used to it you'll think something went wrong during boot.