I have received a 386 mainboard with OPTI chipset. Possibly an early model, since it does not support cache.
The chipset is labeled "82C381P" and "Chipset2".
This is my best guess, but it looks really close. Could it be a Gigabyte GA-386PS?
This block diagram looks very similar:
I couldn't find the actual manual, but there are some jumper setting and connector details here