Like the competing Nvidia GPU, the ATI Radeon HD 2900 XT GPU used in this Sapphire card has not only moved to DirectX 10, but has made the switch to a more efficient unified shader architecture. However, it doesn't stop there. The HD 2900 XT offers a dedicated video decoder, native Crossfire support (eliminating the need for a special 'master' card), adaptive custom filter antialiasing (CFAA), and it also boasts the first true 512-bit memory bus. Our Sapphire card has 512MB of GDDR3 memory, but DDR4 will be available in the future, too.
The new-generation GPU uses 320 dynamic stream processors, rather than the fixed pixel and vertex shaders from ATI's X1900 series. The stream processors can do pixel shading, vertex shading, physics processing and the new geometry shading introduced by DirectX 10. Put simply, geometry shaders allow tough tasks to be accomplished more efficiently, with less strain on the GPU. One such task is dynamic lighting from multiple light sources. With DirectX 10, it's possible to cut back on the amount of data that needs to be handled in such a task. This leads to either faster frames or more complex scenes, both of which are a plus.
Among a few new antialiasing (AA) improvements found in this card, including up to 8x multi-sample antialiasing (MSAA), the most interesting is called custom filter antialiasing (CFAA). Standard AA smooths out edges and 'jaggies' by blending multiple sub-pixel samples into one by using a fixed weight. CFAA also aims to take objects that appear blocky or jagged and smooth them out, but it uses an adaptable weighting system that allows sampling from sub-pixels to be done dynamically, reducing the loss of image quality. The programmable nature of CFAA also allows ATI to update the function's ability through driver changes over time.
As well as all the performance tweaks, the HD 2900 XT is HDCP-compliant and supports HDMI output for both video and audio, and a DVI to HDMI adapter is supplied in the package. The card has a dedicated video decoder, called UVD, which has been designed to handle high-definition formats such as Blu-ray and HD-DVD. This helps offload the CPU when processing these formats.
Although the new performance features are great when using DirectX 9 based tests, the true test is going to be in DirectX 10 applications. We attempted to run the HD 2900 XT through some DirectX 10 games (Call of Juarez and Lost Planet), but we ran into problems. Call of Juarez would not start, and Lost Planet exhibited rendering problems during benchmarking.
In 3DMark 2006, at the default settings (1280 x 1024, no AA and no anisotropic filtering), the HD 2900 XT scored 11,192, and beat the Asus EN8800GTS 640, which scored 9309. But, it's not quite as speedy as the MSI NX8800GTX-T2D768EHD, which scored 11,894. At 1920 x 1200, with 8x AA and 16x anisotropic filtering (AF) it scored 4493, which is quite fast for such a high resolution and good enough to run current games easily.
In FEAR at 1280 x 960, using 4x AA and 16x AF, it averaged 88fps (frames per second), while at 1600 x 1200, using the same quality settings, it scored an average of 63fps, both of which are very playable frame rates.
This card offers everything the competing Nvidia cards offer, and a touch more, at a competitive price. Unfortunately, we were unable to test DirectX 10 games at this time, but we expect to see some promising results.