3.3v card in 5v PCI symptoms?

[Heiroglyph]

I'm trying to figure out why both of my Nvidia cards prevent booting the Amiga.

With either an old TNT M64 or a fresh from the box 6200, the Amiga simply won't boot. A PC sees them with no problems.

I've seen the same result in both a Mediator 4000 and a Prometheus.

Is this a symptom of a 3.3v card in a 5v slot or what?  It's just too weird that all the other PCI cards I have seem to work, but not these Nvidias.

[Heiroglyph]

Both these cards are keyed as universal, but I've seen quite a few reports of cards that claim to be universal that are 3.3v only.

Any other explanations as to why it wouldn't boot?

[Heiroglyph]

So is this the expected symptom?  Failure to boot?  I mean, the PCI backplane drivers aren't even loaded yet.

I assumed that the card would just not show up or wouldn't function.