This was a build with a Ryzen 9 3900X.

But yes, in my main desktop I originally started with a 1600X, and for some reason there'd be times I'd come back to my desktop the next day and it'd be unresponsive, and I'd have to restart it. Upgraded to a different processor, and haven't had an issue since.

Meanwhile, there is definitely a known defect of 1st generation Ryzen under oddly-specific heavy-load situations, and I have suspicion that the one I have may be a defect, per the serial number. But never really followed through completely on the RMA on that one.