Has anyone tried using an FX5200 AGP 3.0 x8 card on an ASUS P2B
motherboard (rev 1.1 or something like that) which is only AGP 1.0, x2,
3.3V? In particular, an MSI FX5200-T128, 64-bit, half height, passively
cooled card (one of an apparently endless number of minor variants of
FX5200 MSI has, judging from their tech support section).

All the info on the web/usenet indicates it should work fine, and the
universal AGP connector of the card (keyed for both 3.3V and 1.5/0.8V)
further affirms this.

But... I asked MSI's tech support and they say "no". I assume their
tech drones are either not very knowledgeable or they have no "official
endorsement" for such usage (although I can't think of reason for them
to do that).