Almost forgot: I have also cleaned the contacts on the NIC with alcohol, but there was no difference.

The last time this happened to me (albeit with an tuner card) was when incompetent me powered it on while two pins which I don't know the function of were shorted. Maybe its an similar case?
Nevermind

kotel wrote on 2025-01-14, 19:32:

The last time this happened to me (albeit with an tuner card) was when incompetent me powered it on while two pins which I don't know the function of were shorted. Maybe its an similar case?
Nevermind

Sounds like an interesting story 😀) care to share? I wouldn't call you incompetent; happens to the best of us.

songoffall wrote on 2025-01-14, 18:02:

I would assume 3COM cards were more compatible than other brands. Are there any known incompatibilities with this particular card and the Intel 865P chipset? Am I missing something?

It's a long shot but try running the NIC configuration program, from DOS, on the PC that it works with. Disable any advanced functions that you don't need like WOL and boot ROM. See if that helps.

songoffall wrote on 2025-01-14, 18:02:

Another thing that surprised me, whenever I plug the NIC into a motherboard, any motherboard, and connect the power wire to the PSU, the yellow light (indicating 100Mbps connection) on the NIC lights up, even though there's no ethernet cable plugged into it.

It has WOL and actually uses +5V standby power. This might or not be the issue but it's one of these cards that should not be installed or removed when the (ATX) PSU is connected to mains. And/or its caps are not discharged. Fully disconnect and wait for LED to go out or press the power button to let the mobo try to start and drain the caps right away. The latter is not recommended with mechanical HDDs, although most have small delay before spinning up so it's usually not that bad.

Deunan wrote on 2025-01-14, 20:44:

songoffall wrote on 2025-01-14, 18:02:

I would assume 3COM cards were more compatible than other brands. Are there any known incompatibilities with this particular card and the Intel 865P chipset? Am I missing something?

It's a long shot but try running the NIC configuration program, from DOS, on the PC that it works with. Disable any advanced functions that you don't need like WOL and boot ROM. See if that helps.

The boot ROM chip isn't installed. Neither is the WOL header. So I didn't think that would be the case. But I'll give it a shot.

Deunan wrote on 2025-01-14, 20:44:

songoffall wrote on 2025-01-14, 18:02:

Another thing that surprised me, whenever I plug the NIC into a motherboard, any motherboard, and connect the power wire to the PSU, the yellow light (indicating 100Mbps connection) on the NIC lights up, even though there's no ethernet cable plugged into it.

It has WOL and actually uses +5V standby power. This might or not be the issue but it's one of these cards that should not be installed or removed when the (ATX) PSU is connected to mains. And/or its caps are not discharged. Fully disconnect and wait for LED to go out or press the power button to let the mobo try to start and drain the caps right away. The latter is not recommended with mechanical HDDs, although most have small delay before spinning up so it's usually not that bad.

That's my usual protocol when installing components, especially RAM. Didn't help, sadly, in this case. It drains the caps too fast to affect the HDDs, I think, not even the fans go on.

At this point in time, I've just moved it to a different build and was thinking of getting a 3com 3c905b-tx for this one, just wondered if there was a known incompatibility - I've been doing network stuff for a very long time, and the only time I've seen something like this was with much more esoteric cards and sometimes there would be 3.3 volt only cards that were not detected on 5v PCI motherboards, but in this case the motherboard and the card are roughly from the same era.

songoffall wrote on 2025-01-14, 20:42:

kotel wrote on 2025-01-14, 19:32:

The last time this happened to me (albeit with an tuner card) was when incompetent me powered it on while two pins which I don't know the function of were shorted. Maybe its an similar case?
Nevermind

Sounds like an interesting story 😀) care to share? I wouldn't call you incompetent; happens to the best of us.

Well, I can share this, but it's not that interesting.
Got an lot of parts as scrap while back. After I tested all of the tapes, IDE drives and gpu's I went over to the PCI expansion cards. Inspected it for broken parts, found nothing. Plugged the tuner in, powered the PC on aaaand... no POST...
Plugged the POST card in, just dashes. After some troubleshooting I found out the tuner had shorted pins. Tried repairing them but made it worse. Now its in my scrap/repair pile.

kotel wrote on 2025-01-15, 05:42:

Well, I can share this, but it's not that interesting. Got an lot of parts as scrap while back. After I tested all of the tapes, […]
Show full quote

songoffall wrote on 2025-01-14, 20:42:

kotel wrote on 2025-01-14, 19:32:

The last time this happened to me (albeit with an tuner card) was when incompetent me powered it on while two pins which I don't know the function of were shorted. Maybe its an similar case?
Nevermind

Sounds like an interesting story 😀) care to share? I wouldn't call you incompetent; happens to the best of us.

Well, I can share this, but it's not that interesting.
Got an lot of parts as scrap while back. After I tested all of the tapes, IDE drives and gpu's I went over to the PCI expansion cards. Inspected it for broken parts, found nothing. Plugged the tuner in, powered the PC on aaaand... no POST...
Plugged the POST card in, just dashes. After some troubleshooting I found out the tuner had shorted pins. Tried repairing them but made it worse. Now its in my scrap/repair pile.

How exactly were they shorted? Was there a dead component, or was there damage to the traces? Hope it didn't kill the motherboard.

As for making it worse - back in the day I've fixed a couple of things until they were properly broken 😁

songoffall wrote on 2025-01-15, 06:25:

kotel wrote on 2025-01-15, 05:42:

Well, I can share this, but it's not that interesting. Got an lot of parts as scrap while back. After I tested all of the tapes, […]
Show full quote

songoffall wrote on 2025-01-14, 20:42:

Sounds like an interesting story 😀) care to share? I wouldn't call you incompetent; happens to the best of us.

Well, I can share this, but it's not that interesting.
Got an lot of parts as scrap while back. After I tested all of the tapes, IDE drives and gpu's I went over to the PCI expansion cards. Inspected it for broken parts, found nothing. Plugged the tuner in, powered the PC on aaaand... no POST...
Plugged the POST card in, just dashes. After some troubleshooting I found out the tuner had shorted pins. Tried repairing them but made it worse. Now its in my scrap/repair pile.

How exactly were they shorted? Was there a dead component, or was there damage to the traces? Hope it didn't kill the motherboard.

As for making it worse - back in the day I've fixed a couple of things until they were properly broken 😁

Pins were dead shorted together. Something must have hit it. I made one go backwards even more bit still they are internally shorted (atleast that's what I think cause no pinouts online for the chip). Board is fine otherwise.