Besides reducing the number of pixel pipelines in RADEON 9600/RADEON 9600 PRO, one other cost-saving measure ATI implemented in the design of the RADEON 9600 core was to shrink its manufacturing process from 0.15-micron to 0.13-micron. The smaller process allows ATI to get more chips per silicon wafer (assuming good yields at 0.13-micron), thus increasing production without higher manufacturing costs. When coupled with the RADEON 9600 PROís 60-million transistor die (nearly half that of the 9500 PRO), ATI is able to produce significantly more cores with each production run. The end result is that ATIís manufacturing cost per chip is dramatically reduced, while at the same time more chips can conceivably be produced.
For RADEON 9600 XT, ATI has added one new ingredient to the manufacturing recipe: low-k dielectric. Low-k dielectric is a material used to insulate the copper circuits within the RADEON 9600 PRO core. This is important, because the new 0.13-micron process packs the circuits within the chip more tightly together. As clock speeds increase, these circuits can begin to interfere with one another in the same way crosstalk can occur on telephone lines. This form of electrical crosstalk can hamper performance and waste power.
Low-k dielectric material is used to encapsulate the copper wires from each other, ensuring better performance (and thus, higher clock speeds) and lower power requirements. The RADEON 9600 XT is the first graphics core to utilize low-k material. When coupled with the lower power requirements of the RADEON 9600 XTís 0.13-micron core, ATI is able to hit high clock speeds without the need of an external power source or a large cooling unit.
New clock speeds
Other than this addition, the RADEON 9600 XT core is largely the same as the RADEON 9600. Both cores feature four pixel pipelines with one texture unit per pixel pipeline, and dual vertex engines. For added performance, ATI has cranked up the core clock frequency of RADEON 9600 XT to 500MHz, an increase of 100MHz from the RADEON 9600 PRO. This change nets the RADEON 9600 XT an additional 400Mtexels/sec in fill rate, an increase of 20% over its predecessor. Despite this, the RADEON 9500 PRO still boasts the highest fill rate thanks to its eight-pixel pipeline architecture.
Meanwhile, memory clock frequency remains unchanged at 600MHz, as does the XTís memory interface, which is 128 bits wide. (ATI will also be producing a RADEON 9600 SE card. This board features a 64-bit memory interface, so buyer beware.) This provides the RADEON 9600 XT core with up to 9.6GB/sec of memory bandwidth, which is just over 3GB/sec shy of the GeForce FX 5600 Ultraís 12.8GB/sec peak. Our card shipped with 128MB of memory, but the chip supports configurations up to 256MB, so itís possible that a board manufacturer may implement a 256MB RADEON 9600 XT board of their own.