[cctalk] oddity or just early 5160 mobo?

I sort of doubt any of these boards were factory supplied this way, but the date codes on the ram in question are consistent with most other ics . the other banks contain chips that are months older, or newer. 64-256KB SYSTEM BOARD 18 TI gold capped 4164-20 chips in banks 0 and 1. Mix of Fujitsu, TI, NEC chips in banks 2 and 3. There are a half dozen numeric codes present on the board. I don't know what any signify.