You've tried with a different 80mhz oscillator, right?
The heat from that short possible ruined the clock crystal.
Since you can post at 33mhz with a different crystal, I'd try getting a new 80mhz one.
The CPU may be damaged too, since if you did have it in the opposite orientation, you created a short circuit.

That the board was posting and running on a different CPU and crystal shows that the board itself likely survived.

DNSDies wrote on 2021-02-01, 22:05:

You've tried with a different 80mhz oscillator, right? The heat from that short possible ruined the clock crystal. Since you can […]
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You've tried with a different 80mhz oscillator, right?
The heat from that short possible ruined the clock crystal.
Since you can post at 33mhz with a different crystal, I'd try getting a new 80mhz one.
The CPU may be damaged too, since if you did have it in the opposite orientation, you created a short circuit.

That the board was posting and running on a different CPU and crystal shows that the board itself likely survived.

Hey, thank you so much for responding!

I did indeed try another 80mhz oscillator. Actually, I tried a bunch of them, and none of them got hot or anything, but I still couldn’t seem to get the board to POST.

I do think the CPU being damaged is an interesting angle, and it’s one I certainly didn’t consider. However, I couldn’t get the TI 486DLC to POST at 40mhz, either. Could that be related?

I am not entirely sure if the model I have is 40mhz-capable, however, as it isn’t speed-graded and I haven’t found many others quite like it. I was under the impression that, perhaps, if I were to run it at 40mhz, it might at worst be an overclock. Is it possible that the chip just won’t post at 40mhz? That would agree with your suspicions and narrow it down to my 386DX-40 being the issue, which I absolutely could see.

Once again, I really appreciate all the help and the reply! Thanks again DNSDies!

I have an FX-3000 as well, and it works fine with an AMD 40mhz 386 processor, but not any 486 processor I've tried.
If you reversed the position of the 386, then you definitely shorted it, since pin A1 is VSS, and the pin the the opposite corner is ground.
If you can, try another processor.

Before that, though, I'd grab a pinout of the 386 socket and check for any shorts, just in case you did fry something elsewhere on the board. Can't tell from your pictures.

DNSDies wrote on 2021-02-01, 22:45:

I have an FX-3000 as well, and it works fine with an AMD 40mhz 386 processor, but not any 486 processor I've tried. If you rever […]
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I have an FX-3000 as well, and it works fine with an AMD 40mhz 386 processor, but not any 486 processor I've tried.
If you reversed the position of the 386, then you definitely shorted it, since pin A1 is VSS, and the pin the the opposite corner is ground.
If you can, try another processor.

Before that, though, I'd grab a pinout of the 386 socket and check for any shorts, just in case you did fry something elsewhere on the board. Can't tell from your pictures.

Interesting! I had a DX2-66 going too, and it worked in the 486 socket. I wonder why yours doesn't like 486s. I actually saw someone else on here mention that their FX-3000 had something similar going on with 486s.

I'll definitely grab a pinout and check for shorts. This may be a dumb question, but how would be the best way to check for shorts? I have a decent multimeter, so would it be a matter of checking for continuity?

I suppose it might be worth grabbing another 386DX-40 and seeing where that leads.

Thank you again for all your help!

This board model can tick at 50MHz.
It is highly unlikely you damaged the crystal oscillator but putting it the wrong way. It will get hot, but that's it.
If two separate CPUs refuse to POST at 40MHz then you should look at RAM and SRAM as the possible culprits.

pshipkov wrote on 2021-02-02, 02:15:

This board model can tick at 50MHz.
It is highly unlikely you damaged the crystal oscillator but putting it the wrong way. It will get hot, but that's it.
If two separate CPUs refuse to POST at 40MHz then you should look at RAM and SRAM as the possible culprits.

Thanks for the suggestion pshipkov!

Jeez, 50mhz!? Wow, that’s quite an overclock for a 386! I don’t actually have any 100mhz oscillators, but I’m considering getting a few now to give that a try, just for sheer curiosity’s sake.

I’ve tried a few variations of RAM and, at the moment, am running the board cache-less. The best 30-pin SIMMs I have are 9-chip 4mb sticks, rated for 60ns. I’ve tried those and they still don’t seem to work. Unfortunately, I’m not too familiar with 386s overall. Are there any particular types of 30-pin SIMM that would be optimal for 40mhz, as far as timings/ratings go?

Thanks again for your help! I’ll keep trying some different SIMMs and see what I can come up with.