Questions about the pci interface

[EZ Ki11]

Hello,
I am looking at getting a Radeon Hd 6790 1 GB card with a 256 bit interface. Will it require more than one PCIe slot or not? and what is the difference between putting it in a PCIe 2.0 x16 slot vs x4?

 

[benski]

It will require 1 slot on the motherboard, and 2 slots on the case, so if there is a card slot next to the PCI-E it will be blocked. and I think PCI-E x4 vs x16 is only like a 5% performance hit in real world benchmarks.