As we revealed in our ATI RADEON X1000 architecture overview (for details see our article called ATI RADEON X1000: Brand-New Graphics Architecture from ATI Explored ), the new RADEON X1800-series visual processing units (VPUs) feature a lot of promising technologies and manage to demonstrate enough potential in synthetic tests. The time has come reveal performance of ATI RADEON X1800 XT and ATI RADEON X1800 XL graphics products in real-world games and benchmark applications in an attempt to find out whether the GeForce 7800-series is endangered by the new lineup from ATI.

But before we proceed, allow us to remind some peculiarities about the RADEON X1800-series of graphics processors.

• ATI RADEON X1800-series is the first family of VPUs shipping commercially made using 90nm process technology at TSMC. The part is also the most complex graphics processing unit (GPU) built to date – it contains 320 million of transistors, a bit more than the most powerful competitor. While the chip is complex enough, thinner manufacturing technology allowed it to be clocked at up to 625MHz, an unbelievable clock-speed before.
• Despite of the fact that the RADEON X1800 features two times more transistors than the predecessor – the RADEON X800 – the number of pixel processors did not increase and the new family boasts with 16 of them. Instead, ATI implemented Ultra-Threading Dispatch Processor that distributes pixel shader workload among the pixel processors and makes efficient use of pixel processors’ arithmetic logic units (ALUs). ATI claims that this architecture helps to achieve a 90% efficiency of the pixel processors on any shader.
• Additionally, ATI has implemented the so-called branch execution unit into each pixel processor, which dramatically increased performance of dynamic branching, a crucial capability of pixel shaders 3.0, on the RADEON X1800 hardware. Particularly, the RADEON X1800 is about 100% faster compared to the GeForce 7800 GTX in heavy dynamic branching benchmarks.
• To further boost performance in applications that use full-scene antialiasing and/or require extreme memory bandwidth, ATI has incorporated the so-called Ring Bus memory controller into the RADEON X1800-series chips. The new memory controller is likely to considerably improve performance in memory bandwidth-demanding cases and provide further flexibility in terms of memory support. For instance, right now the RADEON X1800 XT is equipped with 1500MHz (1.50GHz) GDDR3 memory, but in future graphics card makers may install possibly higher-speed GDDR4 chips.
• ATI’s new architecture allows maximum flexibility when it comes to creating new chips by adding, or subtracting, certain functional units, such as pixel processors, texture module units (TMUs) and others.
• Due to excessive amount of onboard memory – 512MB – on the RADEON X1800 XT, the board consumes about 110W of power, which is the highest power consumption we’ve seen on a single graphics card. Surprisingly, but both RADEON X1800 XT and XL models do not produce a lot of noise with their coolers.
• ATI claims that the RADEON X1800-series of chips are capable of applying FSAA on images rendered in FP16 high dynamic range (HDR) mode, a potentially major quality improvement over the rival’s GeForce 6 and GeForce 7 that cannot use FSAA with HDR. Still, performance and quality levels require to be investigated.
• The developer also added some interesting video functionality called Avivo into its RADEON X1000-series graphics processors. Particularly, Avivo brings hardware-accelerated H.264 decoding, a codec used on next-gen DVD discs, as well as improved video quality.
• The RADEON X1800-series also feature improved quality anisotropic filtering , which advantages could not be observed on the current-generation games , unfortunately. Besides that, ATI also enabled antialiasing for alpha-textures, which does produce better image overall, but is not as good as transparent super-sampling on NVIDIA GeForce 7800 hardware (click here for details).

All-in-all, the RADEON X1800 features everything what it takes to be called a modern graphics accelerator. Let’s see how the new graphics cards from ATI – the RADEON X1800 XT and the RADEON X1800 XL – show up in real life.