Verdict

ATI clearly designed the R580 to be extremely fast in one kind of processing, while keeping the rest of the chip in pretty much the same very healthy state as the R520, at the same clock speeds. Anticipating - which is the key word - games titles with very high reliance on fragment shader processing means that the R580 can almost come off looking too much like the R520.

The R580, moreso than any modern GPU that meets the Direct3D 9 spec, therefore relies on software to show it off. Even current synthetic benchmarks designed to show off theoretical rates in 3D hardware can have a hard time exploiting the tripling in fragment processing ability. That's not to say the performance increases at the same clock speeds as the R520 are invisible. Clearly they're not, especially at the higher resolutions, with gains of up to 30 per cent in the games we tested.

A good glimpse of shader rate throughput in our instruction issue test also gives a clue to where R580's strengths lie. Furthermore, it has no real-world weakness when it comes to comparison with the R520. Vertex processing rate is intact, performance drops for antialiasing and texture filtering are almost identical, and it shares exactly the same feature base, even besting the R520 with a working implementation of ATI's Fetch4 feature.

Therefore it's fair to sum up that the R580, clocked very conservatively, gives a staggering fragment shader rate first and foremost. Following that, its considered engineering means that's followed by balanced assistance to the other major facets of today's modern game rendering, general stream programming and Direct3D 9 games still to come. Double Z-only rate sustained with MSAA, plenty of memory bandwidth in XT and XTX configuration, more than 1GBps for GPU-to-host writebacks for the first time, and very low penalty PS branching seal this particular deal in a big way.

At $649 for the X1900 XTX and $549 for X1900 XT, it'll push X1800 XT and XL down in price in short order, putting the two GPUs and their SKUs in the kind of price place we'd have expected over time, given an earlier R520 introduction. It's just somewhat maddening to see it happen so soon, annoying the early adopter of R520 hardware. UK pricing before VAT is applied is confirmed at £399 for XTX and £349 for XT, on launch day.

The GeForce 7800 GTX 512 is generally bested in all modern games, and Radeon X1000-series products have enough significant image quality advantages to give X1900 XT the nod even if the performance difference was only slight better or even slightly worse than the Nvidia product. We're seeing all the early XT boards come with the 1.1ns BJ11 DRAMs of the XTX, making the XTX a choice only for those with carefree finances.

Will the software needed to show off the R580 to its best come in time, especially with Direct3D 10/Vista games programming already under way at most major developers? Even if it doesn't fully realise its potential, the X1900 is a blindingly fast 3D graphics product with the best IQ possible.

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