card maybe pci 2.1 and your board is pci 1.0? so maybe thats why idk, 😕

Socket 7 boards don't have PCI 1.0. Actually, there never was a PC mainboard with PCI version lower than 2.0. PCI 1.0 was only a recommendation from 1991 but never made it into production. Socket 7 has PCI 2.1 normally, unless it's a very early board from 1995, then it has 2.0.

for whatever reason that card doesn't like those boards.

The card is an AGP card that is adapted to PCI via two bridge chips near the connector.
Maybe those aren't compatible with those boards or BIOSes so the card can't be recognised in POST?
I wouldn't know why that problem would be but if there's a converter involved I'll always assume it doesn't handle something the way bot other devices woul expect it to happen.

In 2001 I upgraded my system with an Asus P55T2P4, running a K6-2+ 475 @ 500, and a Pine TNT2 32 meg graphics card. Since then I've had that same make and model of board with a 64 meg GF4 MX. Both of the boards you listed have the same Intel HX chipset, so it may be something about that particular card. The retro system I'm building right now is based on an MB8500 TTD, and it works fine with a 128 meg 9250SE.

I experience a similar behavior with an pci ati rage 128 and many, if not all, of my socket 7 mobo. I'm no expert but I believe I see the agp-pci bridge chip that Doornkat talk about, maybe the answer reside here. So if those cards only work on pentium 2 and they where released after 1998 then that's a very specific time frame for such a product. Not to mention that most p2 have agp, irc. Maybe it was targeted to people who wanted a second monitor with 3d acceleration and have the agp slot already occupied or the few who would have a p2 without agp.

There should be a clear disclaimer about those cards compatibility as in 1998~1999 I'm pretty sure many people still had an socket 7 computer and would be interested in upgrading them gpu as the implementation of d3d 6 and opengl 1.2 allowed for interesting cpu offloading.