Question about SRAM memory settings (Biostar MB-8433UUC-A Ver 3.1 ) \ VOGONS

Question about SRAM memory settings (Biostar MB-8433UUC-A Ver 3.1 )

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First post, by CJ Grass

Posted on 2026-02-28, 13:51

CJ Grass Offline

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Joined: 2010-12-02, 23:18
Location: Poland

Hello,
I have a question – how to correctly set the SRAM memory on my Biostar MB-8433UUC-A Ver 3.1 motherboard
Below is a photo to illustrate my problem

Now for some details: I have 4 UM61512ak-15 chips with a capacity of 64 KB (65,536 × 8 bits) - total L2 cache: 4×64 KB=256 KB
From what I can gather from the inscriptions on the board, I should set jumpers JP24, JP25 and JP26 - each of them to 1-2 - but JP24 appears to be empty!?!?!
In this thicket, I see JP 22, which consists of 4 pins, an empty space for JP24 and JP23 next to it. JP25 and JP26 are visible at the bottom, but here too the situation is similar: JP26 should also have 4 pins, but it has 2 (even for 512KB Cache settings).

How do you see it? And how to set it up correctly? Because I just bought the board and I know from the previous owner that he couldn't deal with this Cache (errors in DOS with Him), so he disabled L2 Cache in the BIOS.

Reply 1 of 2, by konc

Posted on 2026-02-28, 16:56

konc Offline

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Location: Greece

You are correct that the pins are missing, you can try adding them. It won't hurt anything if it doesn't work as expected. Also check this out at the top left of your photo, it might be just the photo angle, or it might not.

The attachment Untitled.jpg is no longer available

Reply 2 of 2, by majestyk

Posted on 2026-03-01, 04:57

majestyk Offline

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Joined: 2020-12-04, 09:13

Your MB-8433UUC could be some kind of cheapo version, the two address buffer chips U36 and U37 are not populated here. Maybe they had to snatch away certain cache configurations due to this.

Besides that I´m quite sure that the green jumper is JP22, the black jumper left of the green one is JP24 1-2 and the non-populated pins below are for JP24 3-4.

In this case JP 24 is closed 1-2 like it should be for your setup. The jumpering for 256K with 4 chips 64Kx8 is correct.
Only 512K cache is blocked and that´s why JP26 3-4 is also missing.

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