I was the one who did the last investigation into getting the table 
of production date codes and chip revisions from AMD, a few years ago 
(the le.4 man page cvs log should indicate when). They claimed, after 
I waited for the right engineer to come back from a vacation, that 
the information about that had been thrown out ("de-archived"), but 
that various "obsolete part houses" might still have it. I tried 
finding some of them without much luck, but my heart wasn't really in 
it, and I gave up and wrote the addendum to the le.4 man page.

If you're feeling persistent, you might have better luck than I did. 
There were probably hundreds of thousands, if not millions, of the Am 
7990 shipped in its time; I can't imagine that the replacement market 
has completely dried up...

	Erik <fair@clock.org>