Even by ATi and Nvidia’s standards, the pitch of the two graphics card giants’ ongoing battle is particularly high right now. After an extended period when Nvidia had a clear technical lead, the last 12 months have seen the gap close significantly. As Nvidia grapples with preparing its next raft of graphics cards, ATi is sensing an opportunity to open some distance between itself and its rival. Targeted squarely at the gamer market, the X1900 series is the company’s new flagship product – the state of ATi’s art.

ATi hasn’t simply cranked up the new Radeon X1900 XTX and its stablemates with the usual core and memory clock speed boosts, or bolted on another quad of pixel pipelines. Instead, it’s opted to make a daring assessment of how 3D game engine technology has been developing over the past 18 months to two years, and where it’s headed for the next year or so. And it has decided to take a punt on pixel-shading, which could become the single most important factor in determining GPU performance.

By the end of 2006, ATi believes that nearly all new 3D games will use pixel shader instructions, which are moving away from texture-reading operations to arithmetic pixel-processing. So it’s tripled the pixel shading poke of the X1900 compared with its immediate predecessor, the X1800 XT. That’s a monstrous achievement, given that the X1800 itself appeared on the market just three months ago. Of course, the design was originally pencilled in for Spring 2005, so the swift arrival of the X1900 is more a case of ATi getting back on track than accelerating the graphics industry’s insanely rapid product refresh cycle.

Building on success
In most regards, the X1900 carries over the X1800’s core architecture. That means industry-leading 3D image quality, including the capacity to blend and anti-alias high precision textures without painfully slow workarounds – and hence the ability to apply anti-aliasing to all current HDR rendering implementations, a claim no Nvidia GPU can presently make. Likewise, the Radeon X1900 boasts the best anisotropic filtering in town, thanks to a fully angle-independent algorithm that puts Nvidia’s rather nasty shimmering default texture filtering on GeForce 7-series cards to shame.

It also means the X1900 packs the same fancy ringbus memory controller, which ATi claims significantly reduces latency and increases internal bandwidth, compared to competing 256-bit controllers. It even uses a virtually identical board and heatsink design to the X1800 (and hence generates a familiar noise). But, most of all, this new video chipset retains the same basic 16-pixel pipeline, 16-texture unit and 8-vertex processing engine architecture of its predecessor. And since it boasts only 4 per cent extra core frequency and around 7 per cent more memory clock speed, any performance boost will be down to the extra pixel shaders.

Proof in the pudding
ATi’s theory is that additional transistors are better spent on shader units than on full pixel pipes complete with texture sampling units, as in Nvidia’s high-end chips. Looking at our benchmark results, it’s difficult not to agree. We ran the X1900 XTX through more than 50 benchmark tests. And in all but one, it was faster than Nvidia’s GeForce 7800 GTX 512MB. Even more impressively, the gap between the two graphics cards is largest when playing the most graphically intensive games, such as F.E.A.R. and X3 Reunion, at the highest image quality settings. Flick the anti-aliasing switch on, for instance, and the X1900 strides away from the competition.

At over £450, it’s impossible to justify this card in terms of value for money – especially considering the existence of the X1900 XT, a card that is around £50 cheaper but offers over 95 per cent of the performance. But if it’s the fastest single card you seek, look no further.