Crossfire with PCIe x8 vs x16

[dreamie09]

I m plannin on building new pc. thinking about getting ATI 5770 video card and maybe add 1 more 5770 later for crossfire.
My question is:
How much performance will I lose if i get AMD 790X motherboard (which supports dual PCIe x8) instead of 790FX motherboard (supports PCIe x16)?
right now from newegg, price difference between 790x and 790fx is around.. 80 bux.
Is dual x16 PCIe motherboard worth the extra $80 i ll be paying for 790fx?

 

[Maziar]

Not much unless you play at very high resolutions,here is a good review comparing them:
http://www.tomshardware.com/reviews/crossfire-pci-express,2095.html