The mainstream graphics market is where the majority of gamers look for their video card fix. Top-rated cards in this range offer high performance, a cutting-edge feature set, and a price tag that won't break the bank. A mainstream card usually translates into a cut-down version of an enthusiast model, so that consumers receive the majority of feature benefits, but don't get quite the same level of performance. The payoff naturally comes on the price tag, where the overall retail cost is significantly lower than in the high-end or enthusiast markets. In this review, we'll be looking at the ATI Radeon X1600 XT 256MB card, which was part of the X1000 launch, and remains ATI's primary challenger in the mainstream graphics arena.
The Radeon X1600 XT uses the 90nm RV530 core, which is ATI's replacement for the Radeon X600 and X700 lines. The RV530 has a very interesting core architecture, and actually takes a few steps backward, while still working forward in terms of high-end game performance. The number of pixel pipelines is the first surprise, and the RV530 features 4 pixel pipelines (or a pixel quad), which is a drop from the 8 pipes of both the Radeon X700 and GeForce 6600GT. Of course, in today's gaming environment, pixel fill rate isn't what it used to be, and ATI has purposefully added in 3 pixel shader processors per pipeline, for a total of 12, greatly increasing shader performance.
This means that while the pixel fill rate will be lower than corresponding mainstream video cards, the increased shader performance can make up the difference, especially with newer SM 2.0 and 3.0 games. The RV530 includes 5 vertex shaders, which is higher than the GeForce 6600GT and on par with the GeForce 7600GT. The Radeon X1600 XT features 4 texture units, or one per pipeline, which is the standard architecture for mainstream cards, but still a bit low due to the RV530's 4 pixel pipelines. The card's memory interface is a 128-bit external link to GDDR3 memory, which is connected through a 256-bit internal ring bus controller.
The clock speeds are quite aggressive, and ATI has set the Radeon X1600 XT core at 590 MHz, which provides fill rates of 2.36 GPixels/s, 2.36 GTexels/s (standard) and 7.08 GTexels/s (shaded). The first two are only base specifications, and as noted by the third, the greater the shader computations, the better the 12 shader processors will translate into higher performance. The memory speeds are extremely high for the mainstream market, and ATI has set these at 1.38 GHz DDR, placing the Radeon X1600 XT and it's 22.1 GB/s of memory bandwidth right at the top of the mainstream range. The Radeon X1600 XT also includes support for AVIVO, up to 6x AA & 16X AF modes, 3Dc+ texture compression, and ATI's CrossFire multi-GPU technology.
The ATI Radeon X1600 XT 256MB card is a single-slot design that offers a smaller form factor than the X1800 and X1900 cards. The heatsink-fan unit is also standard issue, not taking up too much real estate, and is very similar to previous ATI models. One nice feature of the Radeon X1600 XT is the lack of an external power connector, which not only frees up a power cable or two, but also simplifies installation. The card's backplate features dual DVI-I (dual link for the primary), along with S-Video output. Our Radeon X1600 XT review card utilizes the PCI Express interface, although AGP models are also available through an external bridge chip. Video resolutions are consistent with the line, and rate at up to 2560x1600 for DVI and up to 2048x1536 for VGA.