The sibling comment had it right, it's a Ryzen 7 1700X. The BIOS has been since updated to support fTPM, and that seems to enable upgrading other machines I ha

The sibling comment had it right, it's a Ryzen 7 1700X. The BIOS has been since updated to support fTPM, and that seems to enable upgrading other machines I have. That Ryzen CPU launched in 2017, which means it existed 4 years before the newest Windows wasn't supported. Really, it's this time frame that surprised me. What do we consider a modern kernel? Debian is still shipping a i386 port that should run on a Pentium II. It's old enough to order a beer at a restaurant. "Nearly all x86-based (IA-32) processors still in use in personal computers are supported. This also includes 32-bit AMD and VIA (former Cyrix) processors, and processors like the Athlon XP and Intel P4 Xeon. However, Debian GNU/Linux bookworm will not run on 586 (Pentium) or earlier processors."