ATI Radeon Xpress 200: Performance, PCI Express & DX9 for Athlon 64

Radeon Xpress' Integrated DirectX 9 GPU

Although we generally focus on the performance of desktop chipsets with the fastest discrete graphics solutions, in order to truly be successful in the chipset business, you have to gain significant OEM market share. And what do the majority of computers sold use? Chipsets with integrated graphics.

The integrated graphics core on a North Bridge comprises almost 90% of the die, but despite this figure, in terms of GPU performance, integrated graphics solutions generally perform far worse than even the cheapest discrete graphics solutions. Part of the reason behind this phenomenon is that the major chipset manufacturers (Intel, SiS, VIA) are not graphics companies, and they operate on fairly long 2-year product cycles for major changes in their graphics designs.

When NVIDIA first made an effort to get into the chipset business, they brought their graphics expertise to the market - quickly raising the performance bar with integrated graphics solutions. But with the nForce4, NVIDIA lacks an integrated graphics solution for the Athlon 64 platform, paving the way for ATI's Radeon Xpress 200 to make a splash.

In the past, you could integrate the slowest desktop GPU into a chipset unmodified, but with the extreme complexity and FP requirements of DirectX 9 GPUs, this is no longer possible. The Radeon Xpress 200 features a modified version of the X300 core, modified to have only two operational pixel pipelines. As a desktop part, only having two pipes would be terrible for performance, but keeping in mind that the market for integrated graphics solution is much less performance-conscious, then it's much more acceptable.

With only two pixel pipes, the Radeon Xpress integrated graphics core can render up to two pixels per clock, with the ability of applying one texture operation per pixel per clock. Compared to Intel's Graphics Media Accelerator 900 (the integrated graphics core of the 915G chipset), ATI is actually at a disadvantage here, with the GMA 900 capable of rendering 4 pixels per clock. Where the Radeon Xpress integrated graphics pulls ahead in the specs is in its two hardware vertex engines. Intel's GMA 900 features no hardware vertex acceleration and instead, depends on the host CPU to handle all vertex operations.

The Radeon Xpress 200 is built on a 0.13-micron process, a larger process than what the 110nm process the X300 is built on, and thus, the integrated GPU runs at a slower core clock speed of 300MHz.

Since the Radeon Xpress' integrated graphics core is based on the X300's core, game compatibility - a weakness for Intel's GMA 900 - should not be an issue with the integrated graphics. If you look back at our recent review of NVIDIA's GeForce 6200, out of the 8 games that we tested, only 5 would run on Intel's integrated graphics solution. Given that integrated graphics is usually all that first-time gamers have access to, game compatibility is quite important.