I have seen a lot of cheap boards with PCI-E x 16 and PCI-E x 16 (4x4) any differences between the two? Does it mean I can put two GPUs?
For mining, a pcie X1 slot is fine, a GPU will not fit in it, but you can get cables to convert the slot for reasonably cheap. You don't need nych bandiwdth to the card at all.