MultiGPU Update: Two-GPU Options in Depth

Final Words

There is quite a bit of data here today, and it can be a little bit daunting to sort through. In every test but one, GeForce GTX 285 SLI leads the way in performance. Often the GTX 280 SLI pops up next. That's surprising considering the fact that AMD doesn't have as heavy hitting a single GPU part. And it also doesn't take into account the fact that these two solutions often come in very low in the "value" lineup and not that much higher in performance than something like the Radeon HD 4870 multiGPU options or even the GeForce GTX 295.

The cheaper Radeon HD 4870 X2 often does better than the GTX 295, and often multiGPU AMD options have better value than the highest end single GPU options from NVIDIA. But the real stand out has to be the Sapphire Radeon HD 4850 X2 2GB. This unique card really shined and held it's own all the way up to 2560x1600. While a 1GB 4850 might not make much sense (the extra RAM only really helps at resolutions where the 4850 can't keep up in terms of processing power), the 1GB of RAM per GPU on the 4850 X2 2GB really helps make this single card multiGPU option high end.

The Sapphire 4850 X2 costs less than a single NVIDIA GTX 280 or 285, and performs better than these as well. While the Radeon HD 4870 X2 is viable as high end single card multiGPU option, it competes at a price point beyond NVIDIA's high end. the 4850 X2 really puts pressure on anything that costs between $300 and $400 from the competition. It's very surprising to us that AMD hasn't pushed this configuration and that Sapphire are the only manufacturer to have put one of these out there.

In general, more than one GPU isn't that necessary for 1920x1200 with the highest quality settings, and the Radeon 4870 1GB or an overclocked GeForce GTX 260 core 216 are good options there. Slower single cards are fine for the high quality at 1680x1050 and multiGPU options are basically wasted at this resolution and lower except in Crysis. As we've seen in past tests, only those with 30" monitors will really benefit from multiple GPUs in their system for now. Of course, there are value-add technologies like PhysX and hopefully sooner rather than later OpenCL will attract more developers to GPU computing. But when were talking multiple graphics cards for rendering it's really not worth it without the highest resolution around.

If you want to break it down, the only NVIDIA single GPU solutions we really recommend as an option are the GeForce GTX 260 variants and/or SLI which are on par with the Radeon 4870 512MB and 1GB depending on the games we chose to test. Really the decision comes down to which games you prefer to play and what features you want. Buying a single GPU solution for more than $300 doesn't make sense with the efficiency of the 4850 X2, and the prices on higher performance multiGPU solutions make them a tough sell really. The GTX 285 SLI is the performance leader, but the cost is just huge.

As we mentioned, this is the first of a series of articles that will explore multiGPU performance. The next article will tackle 3-way SLI and 3-way CrossFireX options. The goal is to extend this look into the 3-way realm, looking at scaling from 1 to 3 and from 2 to 3 cards in a system along side pure performance and value. While this will use much of the same data we've looked at today, the focus will be on 3-way and whether or not it has any real practical use.

While we've already seen 2 GPU performance data, we hope that this more in-depth look than usual helps to illustrate the playing field a bit better. AMD (with the help of Sapphire) really has succeeded at their goal of making single card high end options that compete well with NVIDIA's high end single cards. While the Radeon HD 4870 X2 does compete well with the GeForce GTX 295, the 4850 X2 2GB does a great job of offering higher performance than NVIDIA single GPU options and much more bang for your buck at a price point right below the GTX 280.

Our one caveat with AMD remains driver issues. We are happy with Catalyst 9.2 as it competes with the 8.12 hotfix in terms of stability and performance (and it offers more multiGPU support for recently released games). NVIDIA's GeForce GTX 260 core 216 offers good competition for AMD, and driver support issues don't do AMD any favors. Drivers are even more important when it comes to SLI and CrossFire. SLI enjoys much better support from NVIDIA than CrossFire does from AMD. Because of AMD's driver issues, we often have to wait when new games come out to enjoy proper CrossFire scaling with them. And when hotfixes come out it takes more than a month (usually more like two) to fully integrate changes into a WHQL driver. This is quite disappointing and is really the only strike against the Radeon HD 4850 X2 2GB which is in every other way terrific competition for NVIDIA's lineup.

Sometimes you don't get what you pay for, and with less than linear scaling we do see a reduced value from multiple card solutions. Sometimes getting playability at a higher resolution makes this reduced "value" worth it. Sometimes, CPU and system limits can also reduce value for more than one GPU. And sometimes, like in the case of the Sapphire 4850 X2 2GB, we see a single card that costs the same as two separate lower spec'd (in this case lower memory) parts and can therefore offer great scaling and incredible value.

Stay tuned to see how three cards changes the landscape.