Crossfire scaling on a PCI-e 2.0 4x slot

[alexruiz]

Hi everyone. This one should be easy for the experts.
I remember reading an article recently on how crossfire scaled when the second slot was 1x / 2x / 4x / 8x compared to an additional 16x slot.

However, now that I want to re-read the information, I cannot find it for the life of me, and the incompetent google cannot give me good answers.

Does anyone remember where this posted?
If i remmber it correctly, Crossfire on a 1x or 2x pci-e 2.0 slots affected performance, but a 4x was almost at 95%....

Can you help me find the article? I don't think it was anandtech.


Thanks

 

[GuardiaNGR]

I don't have numbers to show or the article to link it for you but recently I made that mistake. Bought 2 4870x2 for Crossfire use on a board with x16/x4 pci-e. The results were pretty much dissapointing. x4 was bottlenecking the whole performance and i had better results with crossfire disabled than with it enabled.

http://forums.anandtech.com/showthread.php?t=2032075

This is my thread. How i solved it? I bought a board with x16/x8 pci-e for future use and a 5870. From my experience, don't even bother except if you're thinking of plugging in low end cards to those x4.

 

[Borealis7]

here's something for you to read: not exactly crossfire, but it should give you an idea of how it reacts

http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/

 

[cusideabelincoln]

The article I think you're thinking of is at techpowerup:

http://techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/

 

[alexruiz]

Borealis7 & cusideabelincoln, thank you very much! You are the best guys 🙂

That is exactly the article 🙂

 

[Phanuel]

I'm curious about the scaling though. I want to know where a PCI-e 12x would place as the difference from 4 to 8 is slightly greater than the difference from 8 to 16. Wonder if we're actually capping out data requirements at 10-13x currently and in the not-so-distant future we finally hit the actual limit imposed by 16x.