https://theretroweb.com/motherboards/s/biosta … 25uuc-a-ver-3-1

https://theretroweb.com/motherboards/?page=1& … 49&cpuSocket1=5

Old question but do these match?

https://th99.infania.net/m/A-B/32867.htm

https://theretroweb.com/motherboard/manual/32867.pdf

Replying ro myself: Yes they match 95%. I have the same board. Just managed to get it to boot with 486dx2/66. Some confusion around cache config and some cpu jumpers. Board only recognizes 128kB cache so far. I will continue testing.

Update: all cache recognized and memtest passed. Apparently there was mismatch between jumpering instructions and motherboard.

486man_ wrote on 2026-03-25, 17:03:

Update: all cache recognized and memtest passed. Apparently there was mismatch between jumpering instructions and motherboard.

Just to help someone in the future, can you post a picture or a simple diagram of the proper jumper config for the amount of cache you have installed? 😀

TH99 is an amazing resource, but there are often discrepancies like this, so it is nice to put any corrections out into the internet as people find them.

You are absolutely right and thanks for reminding.

Cache jumpers are set as follows
JP26 open
JP25 2-3
JP24 1-2

This matches with bank 1 empty setting in manual.
I have both cache banks populated with N341256P-20 chips which, according to google search, are 32k x 8. Tag chip is N341256P-15.

I have interpreted the jumper diagrams in manual so that white dot marks pin 1. Some matching pins carry the mark 1 in MB also.

Otherwise I have the jumpers set according to manual. In MB the jumpers next to RTC chip are marked JP50-52 whereas in manual they are JP14 and 46. They are all open.

I have attached some photos.

Keywords: Biostar MB-8425/33 jumpers