you can put a 16x card in a 1x slot. you just need to either cut a groove in the end of the slot. or, snap the end off of the slot with a flatbladed screwdriver and a hammer.
(for those of you who don't care, or who have someone who really really wants another GFX card in there no matter what - been there, done it, and it works.)
some 4x slots actually have a groove in the end to take 8x and 16x cards already, like on my gigabyte G33 board.
all PCI express cards fit all PCI express slots. just a little physical adjustment might have to be made. just dont expect a 16x card to work at 16x in a 4x slot, as it will only be able to use the PCI express lanes available in the slot.
you can experiment with this with a 16x card in a 16x slot, and taping up the pins on the card so that they don't make contact after looking at a PCI express pin out diagram
like this oneto reduce the number of lanes available.
and yes you can put a v1 card in a v2 slot, and a v2 card in a v1 slot. the only difference is timing. but then the v2 spec of PCI express for both card and board slot, is that they are able to accept v1 timing as well.
--disclaimer--
i take no responsability for any damage that might occur from you taking a metal stick with an edged end (say, a large flat bladed screwdriver, or chisel), and percussive energy emitter (say, a wooden mallet) to the motherboard of a machine.
information provided purely "as is" and on no account to be acted apon unless you are able to take full responsability for your actions after properly researching what you may or may not be about to undertake.
