X1900XT Crossfire Edition

The long wait endured by ATI fans appears to be over. The manufacturer has released its CrossFire-ready Radeon X1900 chipset and shipped it in high volume. The Radeon X1900 series of chips is comprised of the X1900XT and the X1900XTX. The XTX version is the faster of the two. The X1900XT chip runs at 625MHz and its memory runs at 1.45GHz, while the X1900XTX chip runs at 650MHz and its memory runs at 1.55GHz. Both chips have 48 pixel shader processors and 8 vertex shaders. These numbers basically equate to the graphics card having more power to process more effects and textures in order to render scenes with as much realistic flair as possible.

In combination with a CrossFire-enabled X1900XT card, a feature called CrossFire Super Anti-Aliasing (AA) can be enabled. This feature uses both cards to apply AA samples to each scene, effectively doubling the amount of samples used to produce the smoothest lines possible.

We tested an ATI Radeon X1900XT CrossFire Edition card along with an ATI Radeon X1900XTX card in a CrossFire configuration, running on an Intel 975X chipset-based motherboard, in order to gauge how it compares to NVIDIA's high-end SLI solution.

The way ATI's CrossFire solution works is much clumsier than NVIDIA's SLI, for a couple of reasons. Not all ATI cards support CrossFire. There needs to be a CrossFire-enabled "Master" card installed in the system so that another, standard X1900-series card can plug into it. And secondly, the method of connection between the two cards is via an external multi-headed cable. This leaves a ripe old mess of cables at the rear of the system.

To use a CrossFire solution, you need to have a motherboard that uses a Cross-Fire enabled chipset. ATI has its own chipset, the Xpress 200 CrossFire, which is featured on both AMD and Intel platforms. Intel also has its own chipsets, the 955X and the 975X, which both have support for CrossFire.

In our tests, the X1900XT CrossFire Edition card, coupled with an X1900XTX card, realised improvements of 20 per cent in Quake 4, 13 per cent in Doom 3 and 23 per cent in F.E.A.R. over a single-solution Radeon X1900XTX, using maximum anisotropic filtering (AF) and AA settings (16xAA for the CrossFire solution and 6xAA for the single X1900XTX).

Compared to an NVIDIA GeForce 7800GTX SLI setup, CrossFire was approximately 27 per cent faster in F.E.A.R (1280x960 resolution with 16xAF and 4xAA), but in Doom 3 the results swayed towards the SLI solution, where it was approximately 10 per cent faster (1280x1024 resolution and 4xAA).

CrossFire should come into its own with games that use a lot of high dynamic range (HDR) rendering. ATI claims that its cards can render scenes that feature dynamic and more intense lighting as well as shading effects, while at the same time using AA to make lines smoother, which means that future games should be playable with amazing graphical textures and effects.