PCI Express 2.0 vs 3.0 GPU Gaming Performance Review

Wondering about upgrading to the new Ivy Bridge CPU and PCI Express 3.0 platform? Curious to know if you'll be gaining or losing performance? We compare single, dual-GPU, triple-GPU, single, and multiple display configurations on Ivy Bridge PCIe 3.0 and Sandy Bridge on PCIe 2.0 platforms.

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Highest Playable Settings - GeForce GTX 680 3-Way SLI

All of the settings below are what we found as the highest playable and best overall settings for GeForce GTX 680 3-Way SLI on the Sandy Bridge PCIe 2.0 system and Ivy Bridge PCIe 3.0 system. We ran GTX 680 3-Way SLI on three Dell 2408WFP displays to find highest playable setting on triple-display at 5760x1200.


Max Payne 3

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In Max Payne 3 we were able to play this game at the exact same settings on both systems. We found that at 5760x1200 this was with all in-game settings at the highest values and FXAA. We tried 2X MSAA, but with 2X MSAA enabled the game became jerky and choppy in feeling on both systems. This made the gameplay unenjoyable, so we had to back down to FXAA at 5760x1200. This may be a condition of the limited 2GB of RAM per GPU for three video cards with GTX 680 3-Way SLI.

In terms of performance we once again see Max Payne 3 perform faster on the Ivy Bridge PCIe 3.0 system. In this case we are seeing an 8.577% framerate performance improvement using the PCIe 3.0 system over PCIe 2.0. The framerate performance advantage in Max Payne 3 using the PCIe 3.0 system has so far been very consistent between a single GTX 680, GTX 680 SLI, and GTX 680 3-Way SLI.

With GTX 680 SLI it was a 4.23% framerate increase, with GTX 680 SLI it was a 5.572% framerate increase and now with GTX 680 3-Way SLI it is a 8.577% framerate increase. This is interesting as it does show us a scaling increase.


Battlefield 3

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With Battlefield 3 we were also able to play at the same settings on both systems. We found that 5760x1200 was playable with the highest in-game settings. We had to use FXAA though, as when we tried to enable 2X MSAA with all three video cards we received a choppy/jerky performance feeling, we however did not experience this with Battlefield 3 using 2-Way SLI at the same resolution and settings. So we likely have some 3-Way SLI driver issuses here.

Similar to previous results, the PCIe 2.0 system is faster in terms of raw framerates. A closer look at the framerate shows that it is a 1.99% FPS decrease with the PCIe 3.0 system. Again this is within the margin of error for performance, so in effect the performance was the same between both systems in this game.


Batman Arkham City

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In Batman: Arkham City we were able to play at the same in-game settings on both systems. We found that at 5760x1200 we could run 4X MSAA as well as High PhysX.

This is the first time we have seen any framerate performance advantage with the PCIe 3.0 system in this specific game. Here we are seeing that on Ivy Bridge with PCIe 3.0 we are averaging 62.3 FPS while on Sandy Bridge with PCIe 2.0 we are averaging 56.8 FPS. This means that GTX 680 3-Way SLI is 9.683% faster on the PCIe 3.0 system versus the PCIe 2.0 system. This so far is the largest percentage framerate increase we've seen with the PCIe 3.0 system in our testing.

Our GUESS for why all the sudden this game is benefiting the PCIe 3.0 system is the fact that we were able to run High PhysX. With High PhysX enabled the computer is having to move all that extra physics data to one of the GPUs. This is extra data we were not generating previously with the lower PhysX settings. With the High level of PhysX enabled it's pushing the most physics it can to that GPU. That extra physics data has to travel along the same pipeline as all the other data for the GPUs. It stands to reason that a faster pipeline will mean it can get that data in and out faster. This could be the reason for why all the sudden there is an almost 9.683% increase in framerate performance in this game with the PCIe 3.0 platform. PhysX could very well be benefiting from the improved bandwidth as well as the Ivy Bridge IPC advantage. PhysX also reduces the workload of the CPU, so the IPC differences may not be the primary reason why there is 9.683% framerate benefit here. With NVIDIA's PhysX enabled those physics calculations are offloaded from the CPU as a burden, onto the GPU, again moving across the PCIe bus.


Skyrim

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With Skyrim we were able to play at the same settings on both systems. We found that 5760x1200 with 8X MSAA plus FXAA plus 4X TR SSAA was playable on both systems.

Performance-wise, this is the first time this game has also benefited on the PCIe 3.0 system. With the Sandy Bridge PCIe 2.0 system we are averaging 72.2 FPS, with the Ivy Bridge PCIe 3.0 system we are averaging 77.1 average FPS. This is an improvement of 6.787% with the PCIe 3.0 system. We didn't see this advantage with GTX 680 SLI, but possibly adding a third card does have a burden on PCIe 2.0 and with PCIe 3.0 the burden is relaxed. Still, with the 6.787% framerate advantage it doesn't change the gameplay experience. With framerates averaging in the 70 FPS range you aren't going to notice the difference. It is interesting that it does start to show up with three cards in this game though.


The Witcher 2

We had some issues with The Witcher 2 running three cards in NV Surround, which is not uncommon. We believe it's a game issue, but the game sometimes doesn't properly detect the resolution and aspect ratio and even if you set it to run at 5760x1200 it refuses to run across all three screens and stays in just one screen. This issue followed us through on multi-card AMD GPUs as well. So we won't be able to show it for CrossFireX or 3-Way CrossFireX either.


Summary

In summary, there were more interesting results with GTX 680 3-Way SLI. First of all Max Payne 3 was showing a scaling pattern on NVIDIA GPUs. Starting with GTX 680, to GTX 680 SLI, to GTX 680 3-Way SLI we saw percentage improvements in performance on the PCIe 3.0 system versus the PCIe 2.0 system. In Batman we saw a near 10% framerate performance improvement with the PCIe 3.0 system versus the PCIe 2.0 system, but we think that is related to the fact we were able to use the High PhysX setting. When adding PhysX that same data has to follow the same pipelines as everything else, so it makes sense more PCIe bandwidth would allow better performance. Finally, in Skyrim we saw a 6.787% framerate performance improvement when three cards were added. IPC could be affecting this, as that game is rather CPU dependent.

All-in-all, we never saw any performance exceed a 10% advantage with the PCIe 3.0 system. With all the performance under 10%, it is impossible for us to notice the actual performance differences while real-world gaming. All the in-game settings and gameplay experiences were exactly the same between both systems, we only realized "benchmarkable" differences in performance.