Crossfire 16x 4x

If it is PCI-E 2.0 and you go with a x16 and x4 crossfire setup then you will have a rather noticeable drop in performance, or at least you would not be using the cards at their maximum potential. I would suggest go with crossfire on 8x and 8x, its also not perfect though.

Hope this helps!

your 1 one card will be running at 75% performance let me its pcie 2.0 or 3.0 if 2.0 i have seen one case where it was bottlenecked but he was not able to figure out

I was going to buy this motherboard
http://www.gigabyte.com.lk/products/product-page.aspx?p...

It has
1 PCI express 3.0 16x
1 PCI express 2.0 16x @4x

This is the cheapest one support 8x 8x in here..
http://www.asus.com/Motherboards/Intel_Socket_1155/P8Z7...

Is PCI-E 3.0 8x 8x a good choice?

Also i will upgrade my cpu to IB..

Huh?

Get 8x/8x if you can. If not then 16x/4x while not ideal will be fine. It was horrible and bad on PCIe 1.0, but 2.0 doesn't seem to mind. Last I saw I think the scores were about 10% slower then 8x/8x. (meaning if 8x/8x got 60FPS, 16x/4x would be at 54.)

8x & 8x will be worth it. You will be bottlenecked on the 2nd GPU otherwise. Get something like an AsRock z77 Extreme 4. Not very expensive but very good. I own one and I have 2x7950s in CF on it. Runs amazing.

Agreed, it won't be a huge performance hit but if your spending 500-600 bucks on graphics cards you hardly want to be limited by something like PCI lanes  

AsRock motherboards are not available in my country.. Asus and Gigabyte only.   I

was about to buy a gigabyte z68 (can't remember the exact model)which was

cheaper and support 8x 8x but local stores stopped bringing it down. So my only

choice is z77 here.. Price difference between cheapest 16x 4x motherboard and

cheapest 8x 8x is ~116$   So i would save a lot if i go with 4x. is it maximum

10%? No more performance decrease?

It will be there abouts. Some games might be worse.

What country do you live in? No possibility of an international order?