I think "Motherboards" would have been a better section, but o wellz. As for your question, PCI-E x1, x4, x8, x6, etc. are not really used by anything right now, for my best guess, I would put them with competition to PCI-X on Server boards, as the bandwidth for PCI-E x1, x4, etc. is way more than standard PCI and competes with PCI-X. PCI-X right now is mainly used with RAID cards, for the most part.
~~Mad Mod Mike, pimpin' the world 1 rig at a time