Introduction

Since its introduction last summer, NVIDIA’s GeForce 6800 has largely managed to remain the card of choice for gamers in the mainstream price segment.

As you probably know by now, the GeForce 6800 features a 12-pixel pipeline architecture, with five vertex units backing up the pixel shaders. The feature that stands out the most though is the GeForce 6800’s 256-bit memory interface, with four 64-bit memory controllers responsible for keeping the graphics core fed with data.

This feature is what really allows the GeForce 6800 to stand out from its younger sibling, the GeForce 6600 GT. The GeForce 6600 GT sports much higher clocks than the GeForce 6800 (500MHz on the graphics core and memory versus 325MHz core/300MHz memory on the GeForce 6800 256MB) allowing it to compete very closely with the 6800 in performance as long as the visual effects are kept in check, but once eye candy features such as 4x anti-aliasing are turned on, the GeForce 6800 begins to pull away from the GeForce 6600 GT and many other cards in the mainstream segment. This is because the GeForce 6800’s 256-bit memory controller provides considerably more bandwidth than the 6600 GT’s narrower 128-bit memory interface – 22.4GB/sec for the 6800 128MB versus 16GB/sec on the GeForce 6600 GT.

With more memory bandwidth, the GeForce 6800 is better equipped to handle high screen resolution environments and/or memory-intensive operations such as 4x anti-aliasing. This is one of the chief reasons why it became such a popular upgrade solution at the sub-$300 price point.

But NVIDIA wasn’t the only one to integrate a 256-bit memory interface into a mainstream graphics card. Earlier this year, ATI launched their GeForce 6800 competitor, the RADEON X800.

The X800 boasts slightly higher clocks (400MHz on the graphics core versus 325MHz for the GeForce 6800) and performs very closely with the GeForce 6800, with the GeForce board performing better in OpenGL games like IL-2 and DOOM 3, while the X800 outran the GeForce board in D3D titles such as Half-Life 2 and Battlefield 2 (the GeForce 6800 currently runs slightly faster than the X800 in Far Cry, although this wasn’t the case at the beginning of the year). The real clincher for the X800 though was supposed to be its price, with 128MB boards carrying an MSRP of $199 while 256MB cards were priced at $250.

Neither X800 offering really got a chance to take off though due to late availability. By the time X800 boards really hit the market in large quantities, the GeForce 6800 was priced lower and offered the added benefits of SLI and shader model 3.0 support. ATI then tried to up the ante further with the X800 GTO sporting even higher clocks than the X800, but this card hit the market to late to make an impact and with its stealth introduction in September ATI relied too heavily on their board partners to get the message across.

Later this month, ATI plans to take a third stab at the GeForce 6800 with their RADEON X1600 XT. The X1600 XT ships with a 590MHz core clock speed with 12 pixel pipes and 256MB of memory running at a whopping 690MHz. On paper, these figures, along with the X1600 XT’s support for shader model 3.0, appear to challenge the GeForce 6800 like no other ATI offering before...Which is exactly why NVIDIA has decided to preemptively strike ATI first with a new GPU. The GeForce 6800 GS!