ATI Radeon X1900 XTX review - Page 2

Hey you made it to page two, welcome. Right then, as stated ATI's new flagship was developed under codename R580. At last years press-briefing in October 2005 the word was already out though. Rumor was that a new chip designed under code R580 would be released not too long after the release of the new X1000 series and that's where a lot of speculation started. I'm pretty much betting that initially ATI wanted to release this X1900 series even sooner though. Back in September/October there was an architecture design issue that needed to be solved (transistor gate leak) in the X1600 series and I believe that this R580 design might have had that same issue. Once they solved everything, they got back on their feet real quick though. The recently released X1000 family series of cards are doing quite well in the market. Sure they were originally launched a bit to expensive so NVIDIA could counteract that quickly, but once the cards became available ATI made the smart decision to get the overall prices down making the X1000 series quite popular and way more competitive.

Radeon X1900, or R580, is in numerous ways what the R520 should have been when it was launched. R580 uses the same memory controller found on R520, with that wicked 512-bit internal ring bus controller. Externally, the chip addresses memory with 256-bits. The X1900 XTX version comes with a default memory clock of 1.55GHz. As anticipated, the R580 core still features 16 pixel pipelines yet now has 48 Pixel Shader processors. R580 is produced on a 90nm process.

Let's talk transistor count, please make an estimated guess, how many transistors do you think does the X1900 chip have? The X1900 chip my fellow guru's has just over 380 million transistors, that makes you think huh? NVIDIA's 7800 for example already passed 304 million and the X1800 XT I think had 321 million. But yeah, we are now in a stage where we are nearing 400 million transistors. Smaller fabrication processes help the companies do this. That manufacturing process is at the newer 90nm right now.

Why the massive increase of Pixel Shader cores you ask? Simple, rendering cinematic effects as fast as possible and these are being created by pixel shaders.

Here we see the pixel engine .. 12 x 4 - 48 Pixel units, each unit in organized in a quad.

So the increased Pixel Shader capacity of course is the biggest change in the design of this graphics chip architecture. A pixel pipeline pretty much consists of a pixel shader processor, a texture mapping unit (TMU) and a raster operator unit (ROP). ATI has sort of designed their pixel pipelines such that the pixel shader processors are more independent, while NVIDIA has their ROP units independent.

Really you can compare this X1900 product with the X1800 series in almost every way, yet the focus here absolutely with the 48 Pixel Shader units. Each Pixel Shader processor can handle anything from 1 to 5 shader instructions per clock cycle in its various ALUs. With 48 pixel processors the 1900 series has three times more arithmetic shading processing power compared over the previous flagship product, the X1800 XT. ATI believes that the 3:1 ratio of arithmetic to texture units provides the ideal balance for current and future 3D performance.