DirectX 11 yet again

The review of RADEON HD 5800 covers all features of the new version of this graphics API, which works in Windows 7 and Windows Vista (requires Windows Update). That article devoted the biggest segment of its theoretical part to it.

The new version of the API introduced lots of new features, although DirectX 11 is actually an improved and amended DirectX 10. All its innovations are targeted at higher flexibility, performance, ease of development, which must result in qualitative changes in future applications.

DX11 supports multithreaded rendering and new features of DirectCompute, which may accelerate post processing and many other algorithms. Image quality in games will be improved by: tessellation, order-independent rendering of transparent polygons, complex post processing, new features of shadow filtering. Running physics computations and AI algorithms on GPUs via DirectCompute looks very interesting for games.

All theoretical peculiarities of the new API were covered in the Cypress review. In this review we are going to provide only a couple of other screenshots from games. For example, tessellation used to increase the detail level of characters in the last part of STALKER (Call of Pripyat) -- the screenshot taken without tessellation is on the left, the one with tessellation is on the right:

Indeed, outlines have become smoother, it's especially noticeable on some parts of the model. But that's not the best application of tessellation in games, as objects in Call of Pripyat resemble inflatables, like in early n-patches aka TRUFORM. Besides, complexity of character models is sufficiently high in games to avoid sharp angles, and tessellation is of little help here, unless its usage is planned from the very beginning.

Another peculiarity of Direct3D 11 renderer, which appeared in one of patches to the latest STALKER, is DirectCompute11 for more realistic looking shadows. Shadows become more blurry at the edges as it gets farther, that is half-shadows look more realistic. Let's take a look at comparative screenshots from STALKER: Call of Pripyat:

Pay attention to the shadow from a post in two places: where it touches the ground and on the house wall. In the first case the shadow is more distinct for DX11, in the second case -- it is blurry. That is exactly what we can see in real life. However, the difference is not very big, if you don't look into it really hard.

What's 100% positive is the fact that the patch for Call of Pripyat with DirectX 11 support has been already released, and all improvements can be seen in a real game. Unfortunately, the other games cannot boast of it. BattleForge from EA Phenomic got a patch, but it demonstrates no visible changes. And DiRT 2 from Codemasters and Aliens vs Predator from Rebellion haven't been released yet. So there is little use from DirectX 11 so far.

PCI Express 2.1

Although motherboards are now limited to PCI Express 2.0, and PCISIG delayed Specs 3.0, the new family of graphics cards from AMD support PCI-E 2.1. At least in their specifications.

There are not that many differences, as we could have assumed from the increase in the standard version. The main objective of the future Version 3.0 is higher performance, but Version 2.1 can also accelerate data exchange rates in some cases. And some of the changes planned in Specs 3.0 were implemented in Version 2.1. They are added for better support of devices that require fast data transfer rates, such as GPUs.

Let's describe the main changes in PCI Express 2.1 versus PCI Express 2.0.

• Internal Error Reporting -- Information about internal errors has now become available to program code.
• Atomic Operations -- Support for atomic operations that helps distribute tasks between CPU cores and graphics cards.
• Resizable BAR Capability -- Determining the amount of system resources allocated to devices.
• Dynamic Power Allocation -- Software control of power states.
• ID-based Ordering -- Reducing delays caused by non-optimal order of commands.
• Latency Tolerance Reporting -- Improvements in distribution of resources.
• Alternative Routing-ID Interpretation -- Support for more internal functions of devices.

These are only some of changes in the new version of PCI Express. Unfortunately, we cannot test how much faster the new version is compared to the second version of PCI-E -- we just have no appropriate motherboards. We'll run the test, as soon as we have an opportunity.

Data output, power management, other features

The recently announced new solutions from AMD for the Mid End market also support an interesting technology of simultaneous video output to three devices -- Eyefinity. Extended support for multi-monitor configurations (to plug three or six monitors to a single graphics card) may be useful in games and in professional applications.

Video output in the RV8xx was overhauled to support up to six displays (using special modifications of the graphics card) in various combinations. The number of supported monitors depends on a given configuration of the card, it can reach six or three. The GPU has six integrated TMDS transmitters. In usual graphics cards four of them support two Dual Link DVIs, so it's possible to plug up to three monitors to them.

Support for three monitors, unlike two in the previous solutions, is not a very important advantage. Hardly many users of this mid-end card will install three monitors. It's easier to buy one large monitor or a TV set. So this is a useful feature, but it's not an advantage.

On the other hand, the new audio output via HDMI is definitely an advantage. Like the top family, ATI RADEON HD 5700 cards support HDMI 1.3a and high-quality audio transfer (Dolby TrueHD and DTS-HD Master Audio) from Blu-ray via HDMI. While it's not relevant in case of expensive HD 5800 cards, the relatively inexpensive HD 5750 can be used to build HTPC, and that feature will be very useful there.

The new cards support a dynamic power management technology called ATI PowerPlay. Power consumption of the new cards in the idle mode is reduced by lower GPU/memory frequencies and voltages as well as a special GDDR5 memory mode. As a result, HD 5700 cards consume only 16-18 W in the idle mode, it's really very little. Under full GPU load, frequencies and voltage will be set to maximum, and power consumption will exceed 80-100 W, not bad for such performance.

As usual, in the first part of the article we examined theoretical features of the new GPU and its cards from AMD. The next part of the article is devoted to practice. In this part we are going to compare performance of the new Juniper solutions with that of the previous products from AMD and competing cards from NVIDIA.

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