SLI on Sandy Bridge: Performance Review

Conclusion

Running a multi-GPU configuration on a Sandy Bridge system makes it clearer that the corresponding platform is a remarkable performer indeed. Even with just half the amount of maximum PCI-E bandwidth compared to X58 and clocked only at default speed, the Core i7 2600K-P67 combo manages to close in to the 4-GHz Core i7 930 in terms of multi-GPU performance.

From almost all of our test (with one notable exception for DiRT2, where the disadvantage really shows), it seems that the 8x-8x bandwidth limitation does little to reduce Sandy Bridge’s SLI performance. We have two theories that might explain why the Sandy Bridge platform isn’t left too far behind the X58 with its 16x-16x bandwidth configuration:

1. Sandy Bridge has better and more efficient clock per clock performance compared to Core i7 processors based on previous architectures. This helps improving the overall multi-GPU performance.
2. The integrated PCI-E controller that resides within the processor helps reducing data latency as the chipset is bypassed and data goes straight to the CPU, unlike on X58 platforms.

Overclocking the Core i7 2600K to 4,6 GHz further increases its performance to a level well above the 4-GHz Core i7 930. This is especially apparent on games that are highly affected by the CPU speed, such as Crysis Warhead. With one exception for DiRT 2 that is somehow very dependent on the amount of GPU bandwidth, all the games in our test ran faster on the Sandy Bridge platform despite the limited 8x-8x bandwidth. Also remarkable is the amount of Sandy Bridge’s overall system consumption, which again confirms that it’s more efficient than the X58, even when overclocked.

Now, it’s still too early to conclude that the Sandy Bridge is a better multi-GPU platform, but these results are a very good sign indeed. For now, at least you can be confident enough to use more than one graphics card in your brand new Sandy Bridge system.