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Preview: NVIDIA's GeForce 6600 series GPUs

NV43 emerges for the mainstream

WHEN NVIDIA LAUNCHED its GeForce 6800 series graphics processors back in April, company CEO Jen-Hsun Huang emphasized that the GeForce 6 architecture was highly scalable and would soon power a top-to-bottom line of graphics products. As is often the case with new graphics architectures, GeForce 6 was launched at the top with the NV40 GPU and GeForce 6800 series graphics cards. These cards now retail for between $300 and $500, depending on whether you're looking at a vanilla, GT, or Ultra card.

Although hard-core gamers and performance-oriented enthusiasts might not blink at dropping $300 or more on a graphics card, mainstream markets generally prefer something a little cheaper. Heck, there are plenty of cash-strapped gamers and enthusiasts looking for a deal in the $200 range, too.

To extend its GeForce 6 technology down to mid-range markets and more affordable price points, NVIDIA is now introducing the GeForce 6600 series. Based on an eight-pipe implementation of GeForce 6 technology, flavors of the 6600 will arrive at $149 and $199 price points. Sound tantalizing? Read on for more.

The NV43 graphics processor
The GeForce 6600 series is based on NVIDIA's new NV43 GPU. NV43 inherits all of NV40's core features, including support for Shader Model 3.0, 64-bit texture filtering and blending, 32-bit pixel shader precision, and DOOM 3 acceleration UltraShadow II. Where NV43 differs from NV40 is in the number of pixel pipelines and vertex unit. NV43 has eight pixel pipelines and three vertex shaders—half that of NV40.

The "half NV40" mantra is handy for describing NV43's pixel pipelines and vertex shaders, and it's also useful for describing the chip's memory interface. Where NV40 enjoys a wide 256-bit memory bus, NV43 must make do with a 128-bit memory interface. Half the memory bus width translates to half the available memory bandwidth per clock, but that's nothing new in the graphics world. ATI and NVIDIA both segment high-end and mid-range graphics offerings with 256- and 128-bit memory interfaces, respectively.

While we're on the subject, I should mention that NV43 supports up to 256MB of memory. 128MB implementations will probably be the norm, but board vendors have a habit of offering boards with more memory to differentiate themselves from the competition. In the past, mid-range graphics cards with 256MB of memory haven't been much faster than 128MB cards. However, NV43 could have the horsepower to exploit the extra memory at higher resolutions with antialiasing and anisotropic filtering enabled. Newer games like DOOM 3, whose Ultra High detail level prefers graphics cards with 512MB of memory, may run smoother with 256 rather than 128MB of memory.

NV43 will be fabbed by TSMC using a low-k 0.11-micron manufacturing process. 0.11-micron is just an optical shrink of 0.13-micron tech, so it's not a huge leap. However, using a smaller fabrication process will allow NVIDIA to squeeze more chips on to each wafer, which is always good for profitability. NVIDIA won't be the first to use 0.11-micron fab tech, though. The RV370 GPU that powers ATI's Radeon X300 series graphics cards is also made using 0.11-micron fab tech.

Like ATI's RV370, NV43 has a native PCI Express interface. NV43 is NVIDIA's first native PCI-E chip, and cards based on the GPU will initially be PCI Express-only. Although NVIDIA isn't ready to talk about AGP implementations of NV43 just yet, the company will use its bi-directional High Speed Interconnect (HSI) chip to bridge NV43 to AGP at some point after the GeForce 6600's release.

All right, enough about the GPU. Let's talk about how NV43 will arrive on the market.