Or rather why are 1.5v-only slots so common after a certain point (to the point that slots that could support 3.3v AGP cards just stopped existing)? It seems impossible to find a motherboard that has a universal AGP slot, SATA ports, and USB headers all on the same board. I can get two of the three (either SATA and USB but a 1.5v AGP slot or a universal AGP slot and no SATA ports) but all three together just seems like a pipe dream.

Did 3.3v just reach an age where everything that required it was considered too old to be paired with anything that would have those other features? I'm guessing by the time SATA 1.5 Gb/s was starting to appear on motherboards AGP as a whole was at least in its autumn so anything that was still using it only required 1.5v and there was no current generation need to still support 3.3v cards (even though the cards themselves seem only come in 3.3v and universal - I don't think I've seen a 1.5v-only AGP card in my research).