ATI Radeon X1800 XT (Preview)

The Radeon X1800 XT is the flagship model in ATI’s new X1000 family of graphics cards.

It is a direct competitor to Nvidia’s high-end Geforce 7800 GTX card, but has several features that set it apart. It is the first graphics card with a graphics processing unit (GPU) created using a 90nanometer fabrication process.

This allows ATI to achieve a relatively high GPU clock speed of 625MHz, nearly 200MHz faster than a standard Geforce 7800 GTX. The card also uses 512MB of GDDR3 memory running at an effective 1.5GHz.

The X1800 XT uses a different architecture to previous cards ­at the helm of which is a ‘ring bus’ memory controller. This uses eight 64bit memory channels and can manage an application’s requests for memory based on priority. The former flagship ATI card, the Radeon X850, used four 32bit memory channels.

It occupies two motherboard slot spaces and is very long. It gets quite hot and is noisy, although ATI says it can intelligently reduce the speed of its cooling fan in ‘2D’ application mode to run quieter.

The X1800 XT is Crossfire compatible, so can be run in a dual graphics card configuration, much like Nvidia's SLI technology. But because we were able to get hold of a preview card, we could not test this feature because ATI did not have have any Crossfire-enabled versions ready at the time of writing. As soon as these are available we will test them and get the review online.

We were restricted to a beta version of its Catalyst graphics card driver, but it still scored 8,326 in our default 3Dmark test. An overclocked Geforce 7800 GTX scored 8,291 in our tests, while a standard version got 7,729. Running 3Dmark at high resolution (1,600 x 1,200) with 4x anti aliasing (AA) and 16x anisotropic filtering (AF) enabled, the X1800 XT scored 5,556. Our 7800 GTX achieved 4,781.

The X1800 XT doesn't fare as well as the 7800 GTX in OpenGL games such as Doom 3. Using the above settings, the X1800 XT was 10fps slower, but it did better in Direct3D games, which are more common. In Far Cry with 4x AA and 8x AF enabled it scored 72.26fps - ­over 15fps faster than a 7800 GTX.

The X1800 XT isn’t perfect but it shows great promise and it’s also not as expensive as we’d expected. 

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