Conclusion
More than anything, this was meant as a purely academic look at Nvidia’s SLI technology—to compare SLI across two cards to SLI running on one card. We suspected that the PCI Express throughput afforded by two x16 slots would emerge as a slight advantage over a single board with two GPUs running in one x16 slot.
In many cases, it looks like we were right, even if the explanation can’t be solely attributed to PCI Express bandwidth (there’s also the nForce 200 bridge chip and its features to consider, along with the different timings of Nvidia’s SLI link between the different card combinations).
Given the shortage of GeForce GTX 295s in the channel right now, we thought it’d be interesting to see how closely the performance of a GeForce GTX 295 could be matched by two GTX 275s. And the answer, given the GTX 275’s rather substantial clock speed advantage, is that you’ll quite easily outmode a GTX 295 using a couple of 275s—often with frame rates that are 10% higher or more. Moreover, the single-GPU cards are actually cheaper than the premium dual-GPU board. The trade-off, of course, is higher power consumption, the monopolization of four expansion slots on your SLI-capable motherboard, and a less-scalable platform (at least a single GTX 295 paves the way for four-way SLI down the road). The direction you take your own gaming system will naturally depend on a number of different variables, and the practicality of a GeForce GTX 295 might outweigh the performance advantages of two GTX 275s.
Sometimes we just get these little urges to explore the intricacies of the latest and greatest. Having run the comparison of two seemingly equivalent configurations, we’d actually be happiest with the two GTX 275s on an X58-based platform. Or, if you have your eye on the value prize, check out a couple of Radeon HD 4770s on X58 at a price point that cuts these tested setups in half.
