Graphics Cards Guide

GeCube Radeon X1900 GT 256MB review

GeCube Radeon X1900 GT 256MB

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ATI's Third Law

ATI's Third Law

Rumors permeate our everyday life so it's perhaps not surprising that they are widespread in the technology industry. Apple and its cult of followers is a perfect example of a celebrity tech firm that has 'stalkers' keeping track of every development in the Mac arena, with a whole cottage industry of websites that engage in rumors passing off as 'news'.

This situation extends to discrete graphics too as what could be more grist to the rumor mills than the sometimes-unhealthy rivalry between ATI and NVIDIA, the two key players. A history of mutual mudslinging though the media merely adds spice to the competition. It is against this backdrop that we find out from arguably one of the biggest such news sites around – the Inquirer – some interesting new details about ATI's next generation graphics core , the R600. Though extremely sparse on details, the article reveals that the R600 is slated to arrive at the end of the year and promises DDR4 memory along with the usual 'faster and greater' that we have all come to expect from graphics chipmakers and their marketing hyperbole.

Even if it's in the rumors department, ATI surely needs such a boost, because in real life, it's gradually losing market share in the ever-important discrete graphics segment . Though its integrated components have been growing steadily at the expense of Intel, ATI has lost ground in the past months for both discrete and mobile graphics to NVIDIA. Part of that reason as most of you should know by now is NVIDIA's GeForce 7 series, especially the mid and upper range reinforcements like the GeForce 7600 and 7900 GT. These graphics cards have also translated well to the mobile department with good results.

As for ATI, the company has recently been on the defensive, throwing new products to match the competition. The Radeon X1800 GTO was such an example for the middle segment and in quick succession, ATI has lined up another similar offering for the high-end – the Radeon X1900 GT 256MB. Talk about action and reaction.

Just like the Radeon X1800 GTO uses a stripped down R520 core, so the latest addition to the big and happy Radeon family comes with the flagship R580 core found on the Radeon X1900 series. The caveat is that its record high 48 pixel shaders have been cut down to 36 while the texture and raster operation units are both similarly reduced to 12 from the original 16. Essentially, ATI disabled an operating (or damaged, whichever is applicable) quad from the core, thus the uniform reduction of a quarter of the processing units across the chip.

Clock speeds have also been adjusted downwards, with the core of the Radeon X1900 GT running at 575MHz compared to the 625MHz on the XT. The onboard frame buffer has been halved to 256MB and clocked at a slower 1200MHz DDR and not 1450MHz DDR. Fortunately, the rest of the Radeon X1900 architecture remains untouched, from the 512-bit internal ring bus to the eight vertex shaders. With the number of high-end Radeon variants increasing in number, it could be hard to keep track so here's our summary of their features, together with the GeForce 7900 GT, the obvious NVIDIA foil to the new Radeon X1900 GT in the following table:

Radeon X1900 GT Against Competing GPUs
Model ATI Radeon X1900 GT 256MB ATI Radeon X1800 GTO 256MB ATI Radeon X1800 XL 256MB ATI Radeon X1800 XT 256MB ATI Radeon X1900 XT 512MB NVIDIA GeForce 7900 GT 256MB
Core Code R580 R520 R520 R520 R580 G71
Transistor Count 384 million 321 million 321 million 321 million 384 million 278 million
Manufacturing Process (microns) 0.09 0.09 0.09 0.09 0.09 0.09
Core Clock 575MHz 500MHz 500MHz 625MHz 625MHz 450MHz
Vertex Shaders 8 8 8 8 8 8
Rendering (Pixel) Pipelines 12 12 16 16 16 24
Pixel Shader Processors 36 12 16 16 48 24
Texture Mapping Units (TMU) 12 12 16 16 16 24
Raster Operator units (ROP) 12 12 16 16 16 16
Memory Clock 1200MHz DDR3 1000MHz DDR3 1000MHz DDR3 1500MHz DDR3 1450MHz DDR3 1320MHz DDR3
DDR Memory Bus 256-bit 256-bit 256-bit 256-bit 256-bit 256-bit
Memory Bandwidth 38.4GB/s 32.0GB/s 32.0GB/s 48.0GB/s 46.4GB/s 42.4GB/s
Ring Bus Memory Controller 512-bit (for memory reads only) 512-bit (for memory reads only) 512-bit (for memory reads only) 512-bit (for memory reads only) 512-bit (for memory reads only) NIL
PCI Express Interface x16 x16 x16 x16 x16 x16
Molex Power Connectors Yes Yes Yes Yes Yes Yes
Street Price ~US$299 ~US$199 - 249 ~US$349 (All-in-Wonder version) ~US$269 ~US$430 - 479 ~US$279 - 299
Other Information
  • CrossFire Ready
  • CrossFire Ready
  • CrossFire Ready
  • CrossFire Ready
  • CrossFire Editions Available
  • CrossFire Ready
  • CrossFire Editions Available
  • SLI Ready