As you know from our earlier reviews called PowerColor Radeon X1800 GTO Graphics Card: the Best in Its Class?, ATI Technologies’ reply to Nvidia’s GeForce 7600 GT was the Radeon X1800 GTO graphics card that utilized the company’s large stock of R520 chips. A viable attempt at leadership in the $199-249 price segment, this graphics card indeed became one of the best mainstream products, even though not an all-around leader.

The $249-299 segment being occupied by the Radeon X1800 XT 256MB and the Radeon X1900 XT costing as much as $449, there was a great gap between them which couldn’t be filled by the Radeon X1800 XT 512MB due to a number of reasons, the main of which was its out-dated design. An R580-based solution was necessary to offer something really competitive in this price sector because the potential of the R520 GPU with its only 16 pixel processors had been exhausted while the new graphics card was supposed to have better technical characteristics than the Radeon X1800 XT’s, but inferior to the Radeon X1900 XT’s. That’s the background behind the arrival of the ATI Radeon X1900 GT.

It’s a traditional trick of ATI Technologies’ to employ one and the same graphics processor on several graphics card models positioned in difference performance categories. Considering the flexible modular architecture of the Radeon X1000 series on the whole and of the R580 GPU in particular, it wasn’t a big challenge for the company to create a new performance-mainstream product. We know the R580 chip (or Radeon X1000) originally incorporates 48 pixel shader processors, 16 texture-mapping units and 16 raster operators. This 3:1:1 ratio of functional subunits embodies ATI’s current approach to designing graphics processors which is focused on achieving maximum performance at executing pixel shaders with complex math1ematical calculations.

Although the number of functional subunits may vary in each particular Radeon X1000 series GPU, ATI decided to stick to the 3-to-1 ratio in its Radeon X1900 GT. This GPU has 36 pixel processors, 12 TMUs and 12 ROPs or three fourths of what the Radeon X1900 XT has. This is a rather arguable solution considering the performance-related aspects of games we play today. Nvidia’s cards from the GeForce 7900 family have 24 TMUs and 16 ROPs and it will be hard for the newly arrived Radeon X1900 GT to compete with them, especially when full-screen antialiasing is enabled and in scenes with a lot of high-resolution textures or using shaders with multiple texture lookups. On the other hand, ATI claims its new product has a good reserve of performance for upcoming games. The claim sounds logical in view of the tendency towards putting ever more math1ematical operations into pixel shaders.