9th or 10th gen Intel? (on apropos of mobo fire)

[viper37]

If you only changed one part (the motherboard), it likely didn't trigger the re-activation process for Windows.  I think it's the same as for past Windows, up to 3 devices may be changed before there's a re-activation prompt, and it is reset every 4 months.

[Barrister]

When I built a new rig in 2016 I called up Microsoft and they gave me a new serial# to activate windows.

And it was 100% a new build - the old machine was a Mac that I dual-booted.