Crossfire 7950's on 16x/4x......

[chingpot]

Hey LL's,

 

Bought a budget z77 board http://www.gigabyte.com/products/product-page.aspx?pid=4326#ov, just for a cheap solution to overclock my i7 non k.

 

How much loss of performance would I get running dual 7950's on this board compared to say 8x/8x. I know the knee jerk reaction is that x4 would be pants, but realistically how bad would it be, I remember seeing AMD benches ran at 16x, 8x, 4x etc and 4x was about 89% of 16x pcie 3.0 but this was for single cards. Anyone have any accurate benches on crossfire 16x and 4x or any anecdotes on doing this. Any stuttering to expect on 4x.

 

Cheers

 

 

[Excon]

Eh it's not ideal but it would still work fine. I'm like 90% theres a fairly large drop off between 8x and 4x compared to 16x vs 8x

[H4X3R]

No big performance hit.

[chingpot]

10% loss on fps from optimum I can live with but I don't wanna end up with stuttering.

[TheDigitalRealm]

Eh it's not ideal but it would still work fine. I'm like 90% theres a fairly large drop off between 8x and 4x compared to 16x vs 8x

 

Yeah, I'm afraid I'm going to have to agree. From 16X to 8X the performance hit is pretty much margin of error and barely measurable, but move down to 4X and you start really limiting the bandwidth and, from what I've seen, most GPU's become bottlenecked. 

[BiG StroOnZ]

 

 

 

 

 

 

 

 

Performance difference between x16 and x4 are negligible. In the first graphs you can see even with x16 and x16, x16 and x4 aren't that behind framerate wise (if you look at the 3770k using x16 and x4 in Crossfire compared to the 3930k using x16 and x16). With 7950's you are still using a Crossfire bridge, so bandwidth shouldn't be an issue.