You lost two boards due to that card? Scary and upsetting!
Was it advertised as "tested and working"?

Yes it was. But I think a lot of people who say this don't actually test the card. I could not boot I to Windows even once when it did make it past POST.

I don't know who owned this last but take a look at these screws. I'm pretty sure it didn't come like this from the manufacturer.

Please make sure you leave negative feedback, so other unsuspecting potential buyers are warned.

Quite recently I bought a s462 motherboard from eBay advertised as "tested and working". Well, it didn´t.
I contacted the seller about it and he offered a refund. Before leaving negative feedback, try contacting him, If the seller is decent he should act the same way.
Altough that won´t bring back your damaged motherboards...

Con 2 botones wrote on 2021-09-20, 20:49:

Quite recently I bought a s462 motherboard from eBay advertised as "tested and working". Well, it didn´t.
I contacted the seller about it and he offered a refund. Before leaving negative feedback, try contacting him, If the seller is decent he should act the same way.
Altough that won´t bring back your damaged motherboards...

Hopefully OP's boards have a recovery+floppy mode

Kahenraz's experience is horrifying similar to my own: two Gigabyte GA-K8VM800M went dead due to corrupt BIOS but I could not be sure whether the video card (Gigabyte GV-R9000 Pro II) was the culprit.

I worked on this for a couple of hours but wasn't able to trace where the problem was coming from. Something is shorting to ground and when you plug in the molex connector it shunts 12V from the power supply through a capacitor and then brings that to ground too.

I removed all of the shorted capacitors and lifted the legs of any diode that was also showing a short without success. This is a very sick card and I'm not very eager to find a reason to plug it back into something with all that's wrong with it.

I wonder if it's possible for the short to be inside the GPU? Its very strange that it worked intermittently. I only know how to do basic diagnostics for repair and this is as far as I can get.

Kahenraz wrote on 2021-09-20, 22:47:

I worked on this for a couple of hours but wasn't able to trace where the problem was coming from. Something is shorting to ground and when you plug in the molex connector it shunts 12V from the power supply through a capacitor and then brings that to ground too.

I removed all of the shorted capacitors and lifted the legs of any diode that was also showing a short without success. This is a very sick card and I'm not very eager to find a reason to plug it back into something with all that's wrong with it.

I wonder if it's possible for the short to be inside the GPU? Its very strange that it worked intermittently. I only know how to do basic diagnostics for repair and this is as far as I can get.

Killer hardware 🙁

I think it's quite safe to say that the graphics card is doing the damage to the boards since it's happening to 2 different boards (of different make I presume).
If you get to keep the card (for instance if the seller doesn't want you to send the card back) then at the very least LABEL it clearly that it is killer hardware!
I've experienced something similar with a stick of SDRAM and with a HDD, both would kill motherboards (the SDRAM was the worst since it also presented vague problems while any motherboard that the killer HDD was connected to would simply die (no way to make it ever POST again). And with the harddrive the second board was completely my fault for not having clearly labeled it even though I had suspected the HDD after it had killed the 1st board.

I had something similar with a SATA power/data combo. It killed at least four or five SSDs before I realized that the reason they weren't detecting was a result of the cable frying them.

I finally noticed an audible sizzling sound as it powered on that alerted me to the problem.

I had several other cables from the same manufacturer but I threw them all away rather than risk some other short in the future. This would have been before I got into electronics repair and testing so I didn't probe it at the time to see what the problem was.