ATI clearly designed 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 R520, at the same clocks. Anticipating, which is the key word, games titles with very high reliance on fragment shader processing means that R580 can almost come off looking too much like R520!
R580, moreso than any modern GPU that meets the D3D9 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 clocks as R520 are invisible. Clearly they're not without increases, especially at the higher resolutions, of up to 30% in the games we tested, clock-for-clock.
A good glimpse of shader rate throughput in our instruction issue test also gives a clue to where R580's strengths lie. Further, it has no real-world weakness when it comes to comparison with 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 R520 with a working implementation of ATI's Fetch4 feature.
Therefore it's fair to sum up that 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 D3D9 games still to come. Double Z-only rate sustained with MSAA, plenty of memory bandwidth in XT and XTX configuration, more than 1GiB/sec 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 $599 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.
All-In-Wonder Radeon X1900 is due to launch within days, availability is excellent - expect to easily pick one up on launch day and the weeks and months to come - and the performance promise of ATI's new flagship GPU is compelling. It's not quite the performance monster some may have expected, but that's largely down to it being held back by software.
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 slight in either direction, comparatively speaking. 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.
A new high-end GPU with everything going for it, perhaps bar the software to really show it off. Will it come in time, especially with D3D10/Vista games programming already under way at most major developers, is the question. Even if it doesn't fully realise its potential, it's a blindingly fast 3D graphics product with the best IQ possible.
Finally, we've got Radeon X1900 Crossfire to pitch against GeForce 7800 GTX 512 SLI in the coming days, so stay tuned for that.
