Core architecture

As we’ve mentioned previously, ATI’s RADEON X800 XT Platinum Edition utilizes a 16-pixel pipeline architecture. This is twice the number of pixel pipelines found in RADEON 9800 XT and RADEON 9700 PRO. The X800 XT Platinum Edition is clocked at a core clock frequency of 520MHz, the highest of any other 16 pipeline architecture in the industry, including NVIDIA’s overclocked GeForce 6800 Ultra part.

With its 16 pixel pipes and 520MHz core clock, the X800 XT Platinum Edition tops out at 8.3Gigatexels/second peak texel fill rate. This compares quite favorably to GeForce 6800 Ultra’s 6.4 Gigatexels/second and is over 2.5 times the previous high-end flagship, RADEON 9800 XT at 3.3Gigatexels/second.

With 16 pipes, memory bandwidth is even more important. If the graphics core isn’t kept fed with data, all the extra pipes (and fill rate) is essentially wasted.

The last three ATI high-end boards

See the similarities between the 9800 XT and X800?

To prevent this from occurring, the X800 XT Platinum Edition graphics core sits on a 256-bit wide interface to its memory operating at 560MHz (1.12GHz effective). Like core clock frequency, this figure is also higher than any other architecture on the market, providing up to 35.8GB/sec of peak memory bandwidth to the graphics core. ATI has partnered with Samsung, Micron, and other memory manufacturers to equip their X800 boards with GDDR3 memory, which is designed to operate at higher clock frequencies at lower power and heat levels than previous memory types. Our board shipped with modules from Samsung.

The graphics core itself is produced on the same 0.13-micron manufacturing process with low-k black diamond dielectric material as ATI’s RADEON 9600 XT. According to ATI, this process allows roughly 33% more transistors per unit area than the 0.15-micron process used for RADEON 9700/9800. ATI also claims that the new process allows the transistors to run over 100MHz faster with no increase in power consumption or heat generation, allowing ATI to get by with the same cooling and power requirements as previous architectures. In fact, ATI claims that the X800 XT requires slightly less power than RADEON 9800 XT.

Also remember that another key innovation used in TSMC’s 0.13-micron process is the use of copper interconnects. Aluminum interconnects were used at 0.15-micron, which has higher resistance than copper. This means that signals travels faster and with less heat than if aluminum had been used.

With its 16 pixel pipes, X800 XT Platinum Edition is composed of 160 million transistors. In comparison, RADEON 9800 XT consists of 110 million while GeForce 6800 Ultra contains a whopping 222 million transistors! This means X800 XT Platinum Edition should be cheaper to produce than GeForce 6800 Ultra, assuming equal yields.

X800 variants

In addition to the X800 XT Platinum Edition, ATI also offers the X800 PRO. The X800 PRO differs from the XT Platinum Edition in the number of pipelines (which has been reduced from 16 in the XT to 12 in the PRO) and the clocks, which are reduced to 475MHz core and 900MHz memory. Both boards sport 256-bit memory interfaces with 256MB of GDDR3 memory, and the same 160 million transistor count.

Modders will be disappointed to hear that ATI has physically disabled four of the X800 PRO's pipelines, so you won’t be able to enable all sixteen pipelines in the core via software solutions, including flashing to an X800 XT Platinum Edition BIOS. Since the rendering core is split up into independent quad pipes, some pipes can be disabled without affecting the rest of the chip. This will also help reduce manufacturing costs. If a manufacturing defect occurs in one of the 16 pipes, the entire block can be disabled and the card can be sold as a 12-pipe PRO board.

It’s rumored that ATI may eventually provide an 8-pipe X800 SE card, since the architecture can operate in 4, 8, 12, and 16 pipeline configurations this is certainly possible.