Rikintosh wrote on 2021-09-11, 01:23:

Many years ago, I remember there was an incompatibility between agp slots, something that came on a yellow sticker above the slot, warning me not to use 1.5v cards because the slot was 3v, or something like that, but I don't remember what it was .

I found some cards in the trash, and I wanted to test them on my motherboards, I have an intel 478 agp 8x, and a super socket 7 agp 2x, besides another one with a slot I don't know about.

Is there really such a risk? What would it take to damage my hardware?

Have a look here .
https://web.archive.org/web/20210120111910/ht … compat/agp.html

Great reference ! The important parts have to do with Voltage compatibilty. You can blow a board or card by running a wrong voltage compat AGP card in a boards AGP slot. I do not solely trust the slot type but use it as a guide and then read the Vid card and mobo's spec to make sure they can work together.

Thank you

Oh yes, that archive link is a great resource
The keying SHOULD prevent incorrect situations, but some cards and boards were keyed incorrectly.

AGP 2X tallies with 3.3V
AGP 4X is 1.5V
AGP 8X is 1.5V with 0.8V signalling, but ALL 8x cards and motherboard are 4X fallback compliant

You can also find some examples that are "by rule" compatible, but the motherboard and card just will not play ball - compatibility of early 3.3V motherboards can be poor with some "universal" cards