Average Results & PCIe Scaling

As shown on the last two pages, some games show great benefits of running on SLI, and others do not. But if we had picked only games that scaled magnificently with SLI, we wouldn't be doing gamers justice. There are pros and cons of going SLI, and imperfect scaling is definitely one of the more significant drawbacks.

Assuming, however, that you'd like to take the leap into a dual-card solution, does it make sense to buy into Nvidia's marketing hype regarding its new dual-link SLI standard? Well, according to the benchmark averages provided below, it certainly seems so.

AVG

On average, you will enjoy a 3% boost in performance going with dual SLI links, whether they come in the form of two standard bridges or one high-bandwidth SLI bridge. Factoring in cost, that certainly seems to favor the dual-bridge solution, but because procuring a second SLI bridge often means going to a third-party, you might prefer to go direct to the source with EVGA's HB model.

By the way, we thought we'd share one theory on the perceived lack of differentiation between dual 400MHz links and the 1300MHz link provided by the HB bridge. Our guess is that Nvidia designed the new HB standard to scale well with future video card models, which will no doubt be more powerful than the GTX 1080. So while we found that the HB bridge isn't actually superior to dual standard bridges right now, we don't think that should be interpreted as a failure of the HB bridge to live up to its potential. Nvidia's single-link SLI bridge proved effective for over a decade; we assume Nvidia intends for the HB SLI bridge to do the same. 

Conclusion

There are two main takeaways from our latest round of SLI testing. First of all, if you're serious about high-refresh-rate or 4K gaming at maximum detail levels in the latest games, you're probably going to want dual cards running in SLI. This is despite the imperfect scaling SLI typically provides. Perhaps in a few years, we'll see game developers dropping dual-card support entirely, but until then, enough games scale well that it makes sense for extreme gamers to take the leap.

Nvidia SLI

And what about Nvidia's new high-bandwidth SLI specification? Well, it's clear that the dual links really are working, given the clear performance boost they provided in every game we tested (with the synthetic benchmark Time Spy being the sole exception). But we do have some concerns about the fancy bridges that Nvidia and its board partners are trotting out. Consider, for a moment, the various solutions Nvidia is peddling, as shown in the accompanying product image from the GeForce.com website. Our hunch is that Nvidia released this new bridge mostly for marketing purposes, as procuring a second standard SLI bridge isn't all that easy (you can only buy them from third party vendors, which likely collect them from OEMs shipping single-card PCs using SLI-capable motherboards). Since the beginning, Nvidia's SLI licensing scheme has dictated that only motherboard manufacturers can provide SLI connectors in the box; they do not come with video cards. That means that even if you purchase two video cards, you'll still only have one bridge (unless of course you have multiple SLI-capable motherboards in your PC collection!). So Nvidia was faced with a conundrum: it knew that Pascal-based video cards would perform better using dual SLI links, but due to its odd licensing arrangement, purchasers of two Nvidia GeForce cards would come up empty-handed when choosing to go with SLI.

So, in the end, Nvidia released a brand-new bridge, which you can purchase direct from its website. That's convenient for Nvidia, as it probably makes a hefty profit on each HB bridge sold, but it's not that convenient for consumers, as Nvidia's direct retail channel really isn't equipped for high-volume sales, as is evident by the two-month wait we endured for Nvidia's HB SLI Bridge prior to giving up and going with EVGA. But that's not the only problem for consumers. Another issue is that the new rigid bridge isn't configurable for different motherboard layouts, so if your current motherboard has 3-slot spacing between its PCIe x16 slots, but you then upgrade to a new motheboard with 4-slot spacing, you're out of luck.

The System

Now, there is one factor weighing heavily in favor of the new rigid bridges, and that is aesthetics, which we think are pretty darn sweet. Consider, if you will, that Nvidia and board partners already had a brisk trade in LED-equipped hard bridges, like EVGA's LED model and MSI's LED model. They didn't provide nearly as significant a boost in performance (only offering a boost from single-link 400MHz to single-link 540MHz), and yet plenty of gamers probably found them worthwhile based on their looks alone. The EVGA HB SLI Bridge we tested offered not only a nice increase in performance, but also a bottom-mounted toggle allowing users to select white, red, blue, or green LED lighting. So from that point of view, the new HB SLI bridge standard may in fact be viewed as a relatively good value.

Based on the findings in this article, we definitely recommend that gamers rocking current-gen SLI setups (which today means GTX 1070 SLI, GTX 1080 SLI, or Titan X Pascal SLI) use dual SLI links, either in the form of two flexible bridges, or a rigid HB SLI Bridge from EVGA or another board partner. From here on out, we'll be including one of these options in all of the SLI builds featured in our Do-It-Yourself PC Buyer's Guides, as we feel they are a must-have for gamers looking to squeeze every last bit of performance out of their high-end systems.

As always, we have more in store on TBG's Gamer's Bench... next up, we'll be pitting GTX 1080 SLI against the Titan X Pascal in a deathmatch of epic proportions (update: you can see that shootout right here!).

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