Hello!

I have the board: https://theretroweb.com/motherboards/s/siemen … stem-board-d970

Initially, the board did not start because one track was broken. I restored it and the board started up. After which I found 1GB of RAM, and MB successfully saw it (4 * 256MB). Also saw two processors, the VRM was one native, the second from the Compaq server. Almost immediately things began to get weird. Sometimes the board crashed at some POST (unfortunately, I didn’t write it down). It helped to wait a minute and start it again.

Then the memory module stopped working if I installed it in the first slot. But if I installed it in the second slot, the system worked. Then I tried to install the OS and at some point the board stopped starting at all, POST 28 (Phoenix BIOS, RAM error). After some time, I tried to start the board again by pressing the processor. Now it still crashing on POST 28 if the memory stick is in the first slot, but if the memory stick is in the second slot - error 3A, L2 cache. I tried it with three different Pentium PROs - the behavior is the same.

Another interesting point is that the board tries to start if I install the processor in Slot-2, with Slot-1 empty. The errors are exactly the same.

What I tried to do:
- checked the ESR and capacity of all electrolytic capacitors, even removed a couple to check - they are ok.
- checked the tracks with scratches with a multimeter, everything is fine.
- thoroughly examined the board for defects - looks ok.
- tried to take out the battery and close the contacts (reset the BIOS)
- checked RAM Voltage (3.3V)

Maybe you have any ideas what it could be? Thank you!