Hi im looking to buy a second GPU soon and a soundcard, the motherboard i have (XFX 790i Ultra) permits to run two GPU's in the top X16 and the bottom, i dont really want to remove the northbridge fan to squeeze ina soundcard ontop of the first GPU (ASUS Xonar D2X) and i see the third slot has a PCI available as i dont plan to use the third X16 for a while yet. is it possible then to plug a Xonar D2X (PCIe X1) into a traditional PCI slot?
Also on a side note from those who might have this board or have to miss out the middle PCIe x16 and use #1 + #3, will the SLI bridge connector have enough clearence over the soundcard?
You can put a x1 PCIE card into any PCIE slot and it'll work just fine (x1/x4/x8/x16). You can also put a x16 card into a x1/x4/x8 slot if it's open-ended (technically) but it'll only operate at the rated speed. Essentially, if the card physically fits, you're good to go.
As for PCI, no, your PCIE card will NOT work in the PCI slot.