Mobile GPU Faceoff: AMD Dynamic Switchable Graphics vs. NVIDIA Optimus Technology

AMD Compatibility with Recent Titles

Along with performance, we also need to discuss compatibility for the recent releases. In something of a surprise, considering the AMD driver date and the release dates of the various games, we actually managed to run all of the games without major issues on both laptops. However, application based switching didn’t always work for AMD, requiring us to use manual switching in a few instances. There was also at least one instance where manual switching had problems, requiring us to use dynamic switching. We’ll have a video and additional discussion of our concerns with the AMD UI and switchable graphics implementation on the next page, but here’s how the games stack up in terms of compatibility for both AMD and NVIDIA.

In the “works as expected” category, Duke Nukem Forever, Portal 2, and The Witcher 2 all ran without any noteworthy issues. Deus Ex: Human Revolution also ran fine, but there was no way to use application-based switching and have it run on the Intel IGP (no loss, really). The same problem occurred with DiRT 3, but with a few extra glitches. First, there was a black border on the right side of the screen—approximately 80 or so pixels wide—that shouldn’t be there; it was present regardless of resolution and even in windowed mode. Second, in manual switching mode DiRT 3 did not render properly in full screen viewing, but worked in a window. Running in a window is not a good solution, so this is a pretty serious glitch. Super Street Fighter IV: Arcade Edition on the other hand ran fine on the IGP in dynamic mode, but on the dGPU the models wouldn’t animate properly and in general the game was unplayable. The workaround is to use manual switching (which may or may not be supported on all laptops—Sony’s VAIO C supports it, and HP added the fixed function switching option in an updated BIOS for the dv6/dv7 laptops), after which the game runs properly. Also worth noting is that a few titles appear to run somewhat faster in manual switching mode, SSF4 and SC2 being two examples.

Besides the above six “new” titles, it’s important to note that all OpenGL titles are currently unsupported by dynamic switching (e.g. Enemy Territory: Quake Wars, Minecraft, presumably Rage when it launches, and as far as we know all other OpenGL apps/games). The workaround is to use fixed function (manual) switching, similar to what we had to do for Street Fighter IV—which means you’ll want to make sure your laptop supports manual switching in some form. AMD informs us that they have a working solution for OpenGL dynamic switching, but it isn’t fully tested yet. It should come out in an updated driver, hopefully before the end of this year (*cough* Rage *cough*). Then we’ll need to see Sony and HP (and anyone else using AMD switchable graphics) to release their own updated driver, and this feels like more of a question of “if” rather than “when”.

NVIDIA Compatibility and Thoughts

All of our discussions so far have centered on AMD’s Dynamic Switchable Graphics implementation and any problems we encountered. What about NVIDIA’s Optimus Technology? First, we immediately note that NVIDIA is at an advantage here, since the 280.26 WHQL drivers we used are only a month old (and there’s a new 285.27 beta driver from last week available now). While our testing is by no means fully comprehensive, so far the only issue we encountered out of the 16+ tested games is in Total War: Shogun 2. The game runs fine, but we are unable to select the Very High preset. Our best guess is that the game is querying the Intel IGP/drivers and limiting a few settings based on the detected capabilities. (We saw a similar issue in the older Empire: Total War in the past, except the last we checked it was limited to the Medium preset.) For someone with a high-end laptop (e.g. GTX 580M), the Very High settings might be desirable, but for 99% of laptops you’ll need to run at High or even Medium settings to get acceptable performance from Shogun 2. Overall, NVIDIA’s Optimus Technology is clearly the more mature and easier to use dynamic switching technology right now.

The only area I can come up with where Optimus isn’t desirable is if you want to run Linux, which isn’t high on NVIDIA’s list of priorities right now—in fact, they’ve said they’re not even going to bother trying to make Optimus work with Linux. This doesn’t make AMD’s switchable graphics solution superior in Linux, unless something has changed and the AMD drivers (or the open-source initiative for AMD GPUs) have improved since the last time we looked. I also have no idea whether AMD’s Dynamic Switchable Graphics works under Linux; it appears that AMD is doing some extra work in their drivers to make things run under Windows, so they might have the same issue as Optimus under Linux. I can’t say it really matters to me either way, as I don’t run Linux, but if you do feel free to add in your comments on which GPU vendor is better, and any information on how the switchable graphics solutions fare. My hunch is that a discrete-only NVIDIA GPU is still the way to go, and if you’re really into Linux the old-style manual switchable graphics with muxes is the better solution.

Summary of Compatibility

Our list of tested titles is obviously limited—I’m only one person, and even with a month of testing there’s only so much I can do—but so far we have yet to find a title that absolutely would not work on either the Sony or Acer laptops. For Acer (NVIDIA Optimus), nearly all games/applications worked without any extra fiddling, but you may need to manually add newer titles (or wait for NVIDIA to release a profile update). On Optimus, the only choice is to run in dynamic switching mode, but that’s generally fine because it works so well. On AMD, depending on the game you might need to select either dynamic switching or manual switching, and if you’re playing multiple games (or using some other GPU enabled application) you will very likely have to go back and forth during the course of a day of gaming. That may sound reasonable, but a lot of users want something that just works without a bunch of extra fussing around, and AMD is coming up short in that area. So, let’s go through changes and annoyances we’ve experienced in testing the Sony VAIO C, specifically as it relates to AMD’s switchable graphics.