Product Reviews

ATi's previous generation of mid-range GPUs boasted the disappointing X600 and X700, neither of which challenged nVidia's popular GeForce 6600 GT. However, ATi achieved great success with the X800 GTO, a late addition to the previous generation that usurped the 6600 GT's A-List reign. The basic principle behind the X800 GTO line was to take a high-end product, disable some functions and then sell it at a mid-range price. It proved highly successful before, so naturally we were curious to see if the X1800 GTO is anything like its predecessor.

So, while nVidia goes through the trouble and cost of designing a whole new chip for its mid-range 7600 GT, ATi has effectively modified an existing chip. The X1800 GTO has 12 operational pixel shaders to the 16 of the X1800 XL, although it does run at XL speeds with 500MHz core and RAM. This could mean that the GTO chips have suffered manufacturing or silicon defects in a pixel pipeline quad but are otherwise working perfectly. Instead of binning a functional GPU, ATi can keep costs down by selling it at a discounted price to the card makers. It's a sensible move that benefits both ATi and its customers.

The estimated street price for the X1800

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GTO (which, initially at least, will only be released with 256MB of RAM) is around £140 - slightly more expensive than the 256MB version of the GeForce 7600 GT, which will cost around £130. On paper, it looks like the two might be equivalent peformers: while the X1800 GTO has three extra vertex pipelines to manipulate geometry data quicker, the 7600 GT's core runs 60MHz faster and the RAM 200MHz faster.

However, the X1800 GTO has all the revolutionary architectural advances of the X1800 series: a programmable Ring-Bus memory controller to bus data around more quickly and efficient handling of branching when working on pixels. Such is the programmability of the X1800 architecture that we're seeing extra performance being unlocked on every X1000-series GPU with each Catalyst driver revision. Using Catalyst 6.3, we found the X1800 GTO to be 13fps faster than the 7600 GT in Far Cry and 4fps faster in Half-Life 2 at 1,280 x 1,024 with 4x AA and 8x AF. However, we saw 1fps less using the same settings in our intense Call of Duty 2 test. Removing AA and AF produced the same 32fps that we saw with the 7600 GT.

Judged purely on performance, the X1800 GTO just edges ahead. And ATi wins in the case of a tie anyway: X1000 hardware has rotationally invariant anisotropic filtering, which leads to uniform texture blending no matter what angle the texture is drawn at. It's also able to handle AA with HDR without game designers needing to implement the nVidia-specific workaround. Plus, the reference cooler, which will be used by most card manufacturers, is much quieter than that of the 7600 GT. If the prices turn out as indicated, and we aren't ruling out price drops from nVidia, then all the signs are that the extra £10 for the X1800 GTO over the 7600 GT is money well spent.