Since the release of the Radeon 9700Pro ATI have had a firm grip on the 3d graphics market in terms of top performance. Admittedly the Geforce FX made up a great deal of ground between its initial release and current times however Nvidia has never comprehensively beat ATI’s top card during the Direct X 9 era. The graphics market is as fast moving as any other PC technology area and we’ve now had the chance to get a detailed look at Nvidia and ATI’s upcoming cards, the ATI Radeon X800 Pro and the Nvidia Geforce 6800 Ultra.


The Geforce 6800 Ultra

As you can see from the above screenshots the 6800Ultra, like the NV30/35 is a large card. The reference designs main features are the dual slot cooler, two Molex connectors and dual-DVI. The cooler, despite its size, is not overly loud compared to any other card on the market and is actually very light. A radial fan is used and this pushes air over the heatsink which is in contact with the core and memory. The fan is also variable in speed, and surprisingly is louder when booting than we ever experienced in 3d use. The Molex connectors supply the large volume of power that the board requires (approx 120w). With regard to this Nvidia recommend that the user has at least a 480w power supply, we used a 400w supply with the card running off one wire in our testing to see just how much of a requirement this was. Throughout our testing the card worked fine and we never experienced any power related concerns. The Dual-DVI is an excellent feature and something that we would have liked to see on all top of the range cards for a while now. Hopefully most, if not all, of the companies making Geforce 6800 Ultras will keep this feature. Finally, The card features 2 400mhz DAC’s.

On the rear of the card you can see the plate used to hold the heatsink and fan on the card as well as the screws which assist in this. The rear of the card also has a label attached which shows the card is running Samsung 600mhz memory. The layout of the memory is also visible on the rear of the card and is placed in the same way as the 5900/5950 series cards. We can also tell from this ram configuration that 512mb cards will be possible with the NV40. Our sample came clocked at 400mhz core and 550mhz (1.1ghz effective) memory for 3d use.

The 6800Ultra is an AGP card and as with all recent cards runs at AGP8x if you have a motherboard which supports AGP 8x. In the coming months the NV40 core will migrate to PCI-Express the main benefit of which is more bandwidth/throughput between graphics card and the rest of the system.

Highlights of the NV40 Architecture:

The 6800Ultra is based on the NV40 core, a .13micron process chip which is manufactured at IBM. The transistor count on this 130nm silicon process chip is a little over 222 million. (More than any other consumer graphics card and more than even the latest Pentium 4 processors). The memory used on the 6800Ultra is GDDR3 which allows for higher frequencies and cooler running than previous types of DDR memory.

Nvidia have much improved the internal pipeline architecture since the NV30 series cards. The NV30 was based on an 8x1 or 4x2 pipeline architecture dependant on what the card was processing at any given time. For the NV40 the pipeline architecture is increased to 16x1 however can also operate in 32x0 or 8x2. 16x1 will occur when the card is rendering pixels with 1 texture applied and this means the card can process 16 textured pixels at one time. If rendering pixels with 2 textures the card will render at 8 pixels at one time. In situations where there is no colour/texture required, such as shadows, the card will be capable of rendering 32 pixels at any one time.

Like the NV3x before it the NV40 pixel shader precision is 128bit/FP32, the maximum suggested in the DirectX 9 specifications. Where the NV40 differs from the NV3x is in its support of Shader 3.0. Support for Shader 3.0 means that the NV40 is capable of supporting Pixel Shader 3.0 and Vertex Shader 3.0. These two features allow for more precise detail and a higher number of instructions per shader in 3d rendering.

The NV40 also introduces HDRR (High definition range rendering) to the Geforce Series. This technology allows the Geforce 6800 Ultra to render more realistic lighting. An example would be glow around a light source will appear more realistic on the NV40 than previous cards.

Ultrashadow (an openGL only feature) gets an upgrade to version 2 with the NV40. The upgrade allows for faster processing of shadows/lighting effects when compared to the original Ultrashadow. Nvidia are also publicising that Ultrashadow 2 will allow for correct antialiasing of shadow edges meaning that shadows look smoother and less jaggy. As it’s an openGL only feature not all game engines will be enhanced by this feature however Doom3 is an example of a game that will benefit.

Video Processing has also gained a more important focus in the NV40, something that will be further enhanced by the move to PCI-Express. The Geforce 6 series will include Programmable Video Processor, a feature aimed at reducing the CPU load when using video features such as encoding or decoding which can be very demanding on your system. Codec support for programmable video processing will also be upgradeable and as Nvidia identify new format types the codec support can be added to the Nvidia drivers. It should also be noted that the speed of the programmable video processor in the NV40 design is independent of the core speed. This allows manufacturers to create cards in the NV40 range that are as fast as the 6800Ultra in video processing however may not be as fast in 3d use and so adding features specific to certain market segments.

AntiAliasing in the NV40 has changed from that used in previous Nvidia cards. The method has changed from ordered grid multi sampling to rotated grid multi sampling. This move should increase Anti-Aliasing image quality, something Nvidia were criticised for in the last generation. (ATI have used Rotated Grid Multi sampling for a while now and it was widely considered to produce better results over the ordered grid method). At the time of review the 6800 Ultra allows use of 2x, 2xQuincunx, 4x and 8x antialiasing.

The texture filtering capable with the NV40 is Bilinear, trilinear and Anisotropic. Anisotropic filtering is available at levels of 2x, 4x, 8x and 16x.


The Radeon X800 Pro

The X800 Pro is ATI’s 2nd from top range card (the next step up is the X800XT). The Pro version is clocked at 475mhz core with ram running at 450mhz (900mhz effective). Memory on the front of the card (128mb) is not covered by the heatsink as it is cooler running GDDR3. Where the X800 Pro differs considerably from the 6800Ultra and the X800 XT is the pipeline configuration - the X800 is a 12 pipeline design. From the design point of view the screenshots above show that the card requires 1 Molex plug to supply power and has a single slot cooler. As with the previous generation of ATI cards the fan is placed slightly off centre and air is forced across the heatsink to disperse heat from the core. Disappointingly we can also see that the X800 Pro has 1 VGA and 1 DVI port for output to your monitor. 3rd party manufacturers can however choose to use Dual DVI designs if they wish.

The rear of the X800 Pro contains additional memory (128mb) bringing the total up to 256mb. Also placed on the rear of the card is the ATI rage theatre chip which supply’s the board’s video features.

For detailed information on the X800 architecture you can view our X800 XT review.


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