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GeForce3 Under Attack: ATi's Radeon 8500 Previewed

HydraVision - One High End Card With Two Displays

First there was Matrox and its 'DualHead', then came NVIDIA with 'Twinview' and finally ATi launched its own two-display-solution called 'HydraVision'. While Matrox is equipping all of its cards with this practical feature, NVIDIA has so far only equipped its 'value' GeForce2MX-line of cards with a second display outputs (of questionable quality). Radeon 8500 will be the first high end 3D-card with two monitor outputs. It allows every kind of mixture between CRT, digital flat panel and TV, as long as they are only two. Each of the two displays can be driven with its own resolution and refresh rate. Once again I'd like to express my disappointment about the fact that the current test samples do not support this feature as well yet.

'Charisma Engine II' - The T&L Unit Of Radeon 8500

The name 'Charisma Engine II' found in Radeon 8500 stands for the 'fixed function' T&L-engine. The majority of games is still using this path since there isn't a whole lot of software titles available yet that would support vertex and pixel shader programs. Radeon 8500's T&L-engine is very powerful (over 60 Mtriangles/s) and able to process a lot more triangles than the T&L-unit of GeForce3, as you will see in the benchmarks.

'Pixel Tapestry II' -The Pixel Rendering Unit

'Pixel Tapestry II', the pixel-rendering unit, consists of four pipelines and it looks (ATi's information is rather inconclusive) as if 3 texels can be applied per pixel per clock, while twice the amount of texels (6) can be applied per pass (which can take quite a lot longer than one clock cycle). With Radeon 8500's core clock of 250 MHz this would lead to a pixel fill rate of 1 GPixels/s and a texel fill rate of 3 GTexels/s. For some strange reason, two different ATi white papers are claiming two different texel fill rates of 2 GTexels/s or 2.4 GTexels/s respectively. Our benchmarks lead to believe that the actual texel fill rate should be around 2 GTexels/s, making it look as if Radeon 8500 is only able to apply two texels per pixel per clock cycle.