My inoperable IIgs configuration was an empty ROM3 board, no expansions cards, one 3.5 drive attached, a monitor on the RGB port, standard ADB keyboard and mouse. The system crashes within 10 seconds of startup every time, usually (but not always) with screen garbage. My voltage levels read fine, and I've tried two different PSUs just in case.
The same ROM3 board works with every other RAM card I've tried in it (including a modern 8mb card from another maker, a fully populated Apple card, and an AE card), and your card seems to work fine in both of my ROM1 boards. I don't have any extra ROM3 boards to test it in, but since all the other RAM cards seem to work, it makes me suspicious.
I posted a message on your forum about it, but it was still not approved after several days, so I quit checking for a response and bought a different maker's card. I see now that there was a response two weeks later, but I'd stopped checking back by that time.
If you want to send me a replacement and have me return this one, I'll try a different card in the machine and see what happens. But like I said, all three of the other memory cards I've tried have worked fine in the machine. I am reasonably handy with a soldering iron, and I have a 'scope, if you need a little help sussing out what is going on, but my work load is extremely heavy at the moment so I don't know if I have time for a whole lot of in-depth testing. But I am willing to help out a bit if I can.