cf 7870 with x16 and x4

[Paavan]

The 7870 is going for 170 dollars so I want to buy 2 for cf. Unfortunately mo motherboard only has x16 and x4 and people are telling me its not worth it at those speeds. Are they correct.

[ShadyHost]

The 7870 is going for 170 dollars so I want to buy 2 for cf. Unfortunately mo motherboard only has x16 and x4 and people are telling me its not worth it at those speeds. Are they correct.

is it PCI 3?

 

If so it should be fine. PCI 2 might be too slow. 

[Paavan]

its pci express 2.0

[Paavan]

how much preformance will I lose

[7850OC]

10% on each card (20% total) from x4 i think? :ph34r:  (it be like 1% (2% total) from x8 i think in PCIe 2.0), but i am just guessing  :lol:

[ShadyHost]

how much preformance will I lose

I don't know how much bandwidth a 7870 can actually use. I would guess it MIGHT be able to use up x8 PCI 2 so with a PCI 3 board you would be fine since it is double speed. 

 

With PCI 2 in your case you could possibly be bottlenecking the second card with a slower slot. I would recommend a new board if you plan on going this or selling the original 7870 and getting a more powerful card. New board is the best option though because 7870s are pretty solid. 

[Wats]

Ive done this. it's crap. dont do it. 

 

2.0 4x is not enough for a 7870

[kaneandtaker]

I've done it before for 2x 6970s on 16x / 4x

 

DON'T DO IT

 

My experience: Playing Guild Wars 2, my 1st GPU is at 99% load, while 2nd GPU is at 50% load. The 4x lane is obviously bottlenecking the 2nd card. Turing CFX on and off, both setups give me the same fps.

[Paavan]

thanks for the responses, i will be getting a 7970 instead