Do you hear any beeps? And also, what type of graphics card do you have, ISA or VLBUS?

So far I've only had ISA video cards at hand, but today I've just got my first VLB card, so I'll give it a try when I get home. I must also admit I've never thought of attaching a speaker to the board - will try that too 😀...

In my VL 486, there is a VL slot that the card won't work on that. I think it has something to do with primary/secondary slots, but I've not searched much about that. If it doesn't work on one slot try another!

Well, the issue is not about the VLB slots - I just tested the VLB video card and it works in any of the three slots on the mainboard, but it still won't start with 30-pin SIMMs.

Nothing comes out of the speaker (same thing - total silence - happens if I power up the board with no memory at all).

What happens if you start the system using both 30pin and 72pin simms?

Did you change your DRAM configuration jumpers according to the modules used?

There's only jumper JP5 for that, which I obviously considered. However, I'm just back from another testing session in order to answer Markk's last question (there are indeed valid mixed SIMM configs described on that web page).

First test: just 4 x 4MB 30-pin - "oh, teh horror", the thing POSTs! 😮

Second test: again 4 x 4MB 30-pin, but a different "quadruple" - no POST this time. Revert to first quadruple, POST again. Replace one of those with each of the second quadruple, POST each time. Back to quadruple #2, this time it POSTS!

Then tested two more 4 x 4MB quadruples - they POSTed too. Moved to 4 x 1MB - POST again. Moved to another 4 x 1MB quadruple, no POST. Revert to the first 4 x 1MB, POST. Back to 4 x 1MB #2, POST this time.

Somewhere in between I also tested a valid mixed combination, and it POSTed... I can only think of some oxidated pin somewhere in one of the 30-pin SIMM slots.

Turns out in the end I have a good mainboard - I just have to replace the barrel-type battery and it's good to go in a retro system 😀.