GeForce And Radeon On Intel's P67: PCIe Scaling Explored
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Page 1:Are Sixteen Lanes Enough?
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Page 2:Test Hardware And Benchmarks
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Page 3:Benchmark Results: 3DMark 11
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Page 4:Benchmark Results: Aliens Vs. Predator
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Page 5:Benchmark Results: Crysis
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Page 6:Benchmark Results: F1 2010
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Page 7:Benchmark Results: Just Cause 2
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Page 8:Benchmark Results: S.T.A.L.K.E.R.: Call Of Pripyat
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Page 9:PCIe Scaling Summary
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Page 10:Bonus Page: Does CrossFire Work At x16/x4?
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Page 11:Conclusion
Conclusion
We found that Nvidia’s high-flying GeForce GTX 570 suffers around 2% performance loss when using an x8 slot, while the Radeon HD 6950 gives up around 4%. While noteworthy in respect to the negative impact on system value, those losses probably wouldn’t be noticeable in actual game play.
More significant are the losses when using a x4 slot, as expected. The GeForce GTX 570’s relatively significant 9% performance loss is far exceeded by the Radeon HD 6970’s 18% loss. And this is where some builders will hit an advice snag, otherwise known as self-proclaimed experts analyzing an effect and incorrectly deducing the cause.
Tom’s Hardware readers often rely on each other to provide the best technical advice, and the advisor offering the most technically-detailed description often gets the nod (hey, if it sounds fancy, it's more likely to be right, right?). Unfortunately, we often see well-meaning enthusiasts leading less-experienced readers astray. Case in point: we have one pervasive poster who offers exceptionally-detailed explanations of why Nvidia graphics cards need no more than four lanes of PCIe 2.0 bandwidth, citing something about internal PCIe to PCI-X conversion. We've also seen presumed experts tell curious gamers that AMD relies so heavily on its CrossFire bridge that a four-lane slot is ideal for hosting a second card. Today’s test results prove both suggestions completely wrong. We’re hoping that today’s article will be the impetus other advice-givers need to chime-in when the community calls for suggestions on how to best configure multi-card configurations.
Putting aside our concern for the honest knowledge-seekers, we can conclude that minimal performance losses in x8 mode set us up for the perfect logical next-step in our three-part series, where we compare X58 and NF200 solutions to today’s board. Will that 2% to 4% difference remain in SLI? Does the NF200 really hurt graphics performance by adding latency? Will the smaller performance gains of three-way CrossFireX mitigate the performance deficits of its x4 slot? Stay tuned to find out!
- Are Sixteen Lanes Enough?
- Test Hardware And Benchmarks
- Benchmark Results: 3DMark 11
- Benchmark Results: Aliens Vs. Predator
- Benchmark Results: Crysis
- Benchmark Results: F1 2010
- Benchmark Results: Just Cause 2
- Benchmark Results: S.T.A.L.K.E.R.: Call Of Pripyat
- PCIe Scaling Summary
- Bonus Page: Does CrossFire Work At x16/x4?
- Conclusion
But... Who would use anything other than a X16 slot if they had one?
The only real use for a X8 slot would be for sli/crossfire where the addition of a second card should result in an Increase of performance, not a decrease.
3 way would be preferable because if performance is still adequately faster I'll consider it.
http://www.tomshardware.com/reviews/pci-express-scaling-p67-chipset-gaming-performance,2887-10.html
The numbers were there all along!
Well, you should probably read the linked page too then. There's no point in artifically creating a configuration (by taping lanes or whatever) that doesn't exist in real life, is there?
"While Nvidia prevents SLI from functioning on PCH-hosted lanes, x16/x4 configurations are completely possible in CrossFire. But should they be? We tested our motherboard in both x8/x8 and x16/x4 configurations to find out."
http://www.tomshardware.com/forum/2887-56-geforce-radeon-intel-pcie-scaling-explored
I'm going there to delete your quote from my response.
I means, its logical, but mayb not true
Just my 2 cents
Of course, Tom's Hardware has all the cool kit that helps editors overcome those bottlenecks.
that's an interesting question, like a 6950 and a 6970, would it be faster with a 6970 in the first pcie slot or the second.
It might be worth conducting at least two way Crossfire/SLi tests more often in future with new card reviews or, at least, follow-up reviews, though I can imagine it'll delay such articles a little. Perhaps using AMD cards on P67 is limiting their scaling, even if it's already very good (with the 6000 series)? Would using two mid-range cards have the same effect?
This is a mighty popular game. Does EA make reviewers pay them to mention their game in reviews?
For example, would this be the case on LGA 1366, where all the PCIe lanes are on the chipset, and not some going through the chipset and some being part of the CPU package? In real world situations, it's not so important because you'd have less cause to use an x4 in LGA 1366, but for academic purposes, and a better understanding of what's really going on, it could be interesting.