3.3V PCI Slot?

I have a PCI card that requires both 3.3V and 5V ("Power Requirement" - Page 4) supply from the PCI bus to operate. I'm trying to determine whether the card is bad, or if it's a voltage supply issue. In my search I've found this picture that specifies the difference between a slot keyed for 3.3V and one keyed for 5V:

I've also read on the PCI-SIG website that "new" PCI standards (2.3 and 3.0) have basically eliminated support for 5V ONLY cards.

Now, the PCI slots on my computer's backplane seem to be keyed for 5V, as do all of the pictures I can find of current motherboards, such as this one:

My question is, are these slots, which are apparently keyed for 5V, the current standard slot? More importantly, although they appear to be keyed for 5V, they will supply 3.3V correct?

I'd find it hard to believe that no new motherboards would have slots that fit the current standard (3.0) if these slots are in fact only 5V supply.....