Final Words
For now, AMD does seem to have an advantage in Call of Juarez, while NVIDIA leads the way in Company of Heroes and Lost Planet. But as far as NVIDIA vs. AMD in DirectX 10 performance, we really don't want to call a winner right now. It's just way too early, and there are many different factors behind what we are seeing here. As the dust settles and everyone gets fully optimized DirectX 10 drivers out the door with a wider variety of games, then we'll be happy to take a second look.
The more important fact to realize is that DirectX 10 is finally here. While developers are used to programmable hardware after years with DirectX 9, there is still room for experimentation and learning with geometry shaders, more flexibility, lower state change and object overhead, and (especially) faster hardware. But DirectX 10 isn't an instant pass to huge performance and incredible effects.
Let's look at it like this. There are really three ways a game can come to be in DirectX 10, and almost all games over the next few years will ship with a DX9 path as well. The easiest thing to do would be a straight port of features from DirectX 9 (which should generally be slightly faster than the DirectX 9 counterpart if drivers are of equal quality). We could also see games offer a DirectX 10 version with enhanced features that could still be implemented in DX9 in order to offer an incentive for users to move to a DX 10 capable platform. The most aggressive option is to implement a game focused around effects that can only be effectively achieved through DirectX 10.
Games which could absolutely only be done in DX10 won't hit for quite a while for a number of reasons. The majority of users will still be on DX9 platforms. It is logical to spend the most effort developing for the user base that will actually be paying for the games. Developers are certainly interested in taking advantage of DX10, but all games for the next couple years will definitely have a DX9 path. It doesn't make sense to rewrite everything from the ground up if you don't have to.
We are also hearing that some of the exclusive DX10 features that could enable unique and amazing effects DX9 isn't capable of just don't perform well enough on current hardware. Geometry shader heavy code, especially involving geometry amplification, does not perform equally well on all available platforms (and we're looking at doing some synthetic tests to help demonstrate this). The performance of some DX10 features is lacking to the point where developers are limited in how intensely they can use these new features.
Developers won't write code that will work fine on one platform and not at all on another. The decisions on how to implement a game are in the hands of the developer, and that's where gamers rightly look when performance is bad or hardware and feature support is not complete. Building a consistent experience for all gamers is important. It won't be until most users have hardware that can handle all the bells and whistles well that we'll see games start to really push the limits of DX10 and reach beyond what DX9 can do.
In conversations with developers we've had thus far, we get the impression that straight ports of DX9 to DX10 won't be the norm either. After all, why would a developer want to spend extra time and effort developing, testing and debugging multiple code paths that do exactly the same thing? This fact, combined with the lack of performance in key DX10 features on current hardware, means it's very likely that the majority of DX10 titles coming out in the near term will only be slightly enhanced versions of what could have been done through DX9.
Both NVIDIA and AMD were very upset over how little we thought of their DX10 class mainstream hardware. They both argued that graphics cards are no longer just about 3D, and additional video decode hardware and DX10 support add a lot of value above the previous generation. We certainly don't see it this way. Yes, we can't expect last years high end performance to trickle down to the low end segment. But we should demand that this generation's $150 part always outperform last generation's.
This is especially important in a generation that defines the baseline of support for a new API. The 2400 and 8400 cards will always be the lowest common denominator in DX10 hardware (until Intel builds a DX10 part, but luckily, most developers will ignore that). We can reasonably expect that people who want to play games will opt for at least an 8600 or a 2600 series card. Going forward, developers will have to take that into account, and we won't be able to see key features of games require more horsepower than these cards for the next couple years.
AMD and NVIDIA had the chance to define the minimum performance of a DX10 class part higher than what we can expect from cards that barely get by with DX9 code. By choosing to design their hardware without a significant consistent performance advantage over the X1600 and 7600 class of parts, developers have even less incentive (not to mention ability) to push next generation features only possible with DX10 into their games. These cards are just not powerful enough to enable widespread use of any features that reach beyond the capability of DirectX 9.
Even our high end hardware struggled to keep up in some cases, and the highest resolution we tested was 2.3 megapixels. Pushing the resolution up to 4 MP (with 30" display resolutions of 2560x1600) will absolutely bring all of our cards to their knees. We really need to see faster hardware before developers can start doing more incredible things with DirectX 10.
I'll stick with DX9 for a little longer methinks till I really really have to switch.