PSA for those of you thinking about lapping your Ryzen 3000.
In one word: ugh
This chip (3900x) has the most infuriatingly difficult-to-remove nickel plating I've ever experienced. My 7700k was a cakewalk compared to this thing. Two 220-grit sheets of carbide wet/dry paper and I still didn't quite get rid of all the nickel plating. Got metal shavings and crap all over the pins too. What a fiasco. Fortunately, I was able to remove the brownish-grey schmutz from the pins with a child's toothbrush (Equate brand) and some 91% isopropyl alcohol. So it probably still works. I hope. I'll have to test-boot it later or . . . something.
Not sure if I'm going to bother lapping it any further since the only goal was to get rid of the nickel . . . not to make it smooth. Conductonaut will resurface the IHS anyway. Or at least it should. CLU always did on copper.
edit: gah, chip seems to be dead. No post. Time to order another one! Yay! Got one from a scalper. This is getting expensive.