Web-site [H]ard|OCP published preliminary specifications of graphics cards powered by RADEON X800-series of visual processing units. Apparently, the products will differ from each-other not only by core-clocks, but also by the number of rendering pipelines.

ATI Technologies’ chip known as R420 will be called RADEON X800 and is likely to be launched on the 26^th of April, 2004. Higher-speed flavour of the R420 – the RADEON X800 XT – is expected to debut on the 31^st of May, 2004, if the assumptions posted last week are correct. PCI Express x16 solution powered by the R423 architecture – RADEON X880XT – will see the light of the day on the 14^th of June. Besides, there will also be a cost-effective version of the R420.

Visual processing unit code-named R420 is ATI Technologies’ next-generation DirectX 9-supporting graphics chip.

[H]ard|OCP reports that various versions of the R420 will be branded as RADEON X800 PRO, RADEON X800 XT, RADEON X880 XT and RADEON X800 SE citing a “classified ATI document”. The solutions will enable different number of rendering pipelines: 12, 16, 16, 8  and will function at clock-speeds of 500MHz, 600MHz, 600MHz and 450MHz respectively. Higher-end graphics cards will have 256 or 512MB of GDDR3 memory functioning at 1000 and 1200MHz for “PRO” and “XT” parts. The performance-mainstream offering RADEON X800 SE will boast with 800MHz DDR memory with 128-bit bus.

Sources familiar with the company’s roadmap revealed Thursday, the 8^th of April, that the 420/R423 graphics processors will have 16 rendering pipelines, significantly more compared to the previously released information about 8 or 12 pipes. Apparently, the company’s future chips have the same capability of enabling and disabling pixel pipelines like the predecessors – the R300 and R350/R360 chips – which were capable of working either with 4 or 8 rendering pipelines. Initially the company believed that 8 pixel conveyers would be enough to stay competitive against the rivalling NVIDIA NV40 chip, however, at this point ATI wants to expose all capabilities of the RADEON X800-series chips to fight with the competitor.

A lot of graphics cards based on R300 and R350/R360 chips with 4 pipes enabled could be tweaked to turn on the remaining 4 pixel pipelines, a modification that dramatically improved performance. Computer hardware enthusiasts are likely to pay a lot of attention on the RADEON X800 SE and RADEON X800 PRO graphics cards that will enable only 8 and 12 pixel pipelines out of 16 respectively.

There is a controversy over a number of transistors in the ATI R420 graphics processor. Initially there was a claim about “more than 200 million of transistors” from Synopsys, the company from whom ATI Technologies acquired its design-for-test software for its “high-end 0.13 micron processor” in mid-2003. In mid-February 2004 an unofficial source reported that R420 contained 160 million of transistors. Now [H]ard|OCP claims about 160 to 180 million of transistors.

Representatives for ATI Technologies usually do not comment on unreleased products.