I looked thoroughly at the board, and aside from the N1996 silk-screened mark and the ACER logo, there is absolutely no model number anywhere... just a bunch of serial numbers on stickers that return no results on Google.
One sticker has the bios info: 686 Amibios ©1999 VQ78 3682 . Another sticker has the manufacture date 2008-03
Here's an image of the board in question:
All the capacitors look perfectly good, the socket is indeed for a LGA775 pinless processor. It's a shame because it's a really nice mobo, The only thing I haven't tried is swapping the power supply, with a 24-pin main connector and 4-pin aux 12v connector.
PS: no tags at the back of the case, but the front sticker bears the model number AM1640-E1404B