I’ve cleaned the board thoroughly and done a detailed inspection under a microscope but haven’t found any damage.

What could be causing the first ram slot not to work?

Could it be related to the floppy port that is not working either?

Is there such a thing as an SDRAM slot tester that I could insert into the faulty slot to try to determine which contacts have an issue?

With such a diagnostic, I could follow the traces to see if I can find components that are faulty.

The memory slot that has an issue is the one closest to the north bridge.
It’s possible that there is a broken solder joint under the bridge, in which case I will not be able to fix it but it would be helpful to narrow down the fault rather than making such assumptions.

I have measured each and every pin of the faulty memory slot to ground and the readings are the same as the other slots.

Why would this one slot cause the system to beep repeatedly and not POST, while the other two slots work just fine?

The only other slightly unusual thing is a whistle or whine from the coil behind the CPU slot, nearest to the AGP port.

I would really like to fix this board. Please help!

This motherboard was the one I had in the early 2000s with a 700MHz Pentium III, still have it, but avoid using for a build.

SDRAM slots are basically wired in parallel, except for some control signals like /WE, /CSx, /CAS, CKx (clock) etc. Compare the data (64) and address (14) bus pins of the first slot with the pins of the other slots, they should all be wired in parallel, if everything is fine here, then the problem is somewhere in the control or clock signals. I recommend checking pins from the top of the slots, not the bottom, this way you'll be sure that there are no cracked/dry solder joints.

SDRAM pinout site, the 72 ECC column should match the SDRAM slot pinout of this motherboard.

SSTV2 wrote on Today, 03:16:

This motherboard was the one I had in the early 2000s with a 700MHz Pentium III, still have it, but avoid using for a build.

SDRAM slots are basically wired in parallel, except for some control signals like /WE, /CSx, /CAS, CKx (clock) etc. Compare the data (64) and address (14) bus pins of the first slot with the pins of the other slots, they should all be wired in parallel, if everything is fine here, then the problem is somewhere in the control or clock signals. I recommend checking pins from the top of the slots, not the bottom, this way you'll be sure that there are no cracked/dry solder joints.

SDRAM pinout site, the 72 ECC column should match the SDRAM slot pinout of this motherboard.

Thanks for the info and the link.

Since the slots are wired in parallel, would it be a fair assumption that the connections are good under the north bridge because the other two slots are working?

With the board not powered, I did measure the contacts of the slots from the top the other day and compared the results to the other slots. The readings were the same but I’ll do it again.

Which components on this board would be part of the control and clock signals? I’d like to check the components to see if I can find anything strange.

I’m waiting on an oscilloscope that I ordered. Hopefully it will help.

Out of interest, why do you avoid using the board in a build? It seems like a nice board. Did you have some issues with it?