Introduction

The evolution of G70

Last June, NVIDIA launched the GeForce 7800 GTX, the company’s first GPU to be built on NVIDIA’s second-generation shader model 3.0 architecture (dubbed CineFX 4.0) and the first product in the GeForce 7800 family. Thanks to its brand new G70 graphics core, the GeForce 7800 GTX delivered considerably more performance than any other graphics card on the market, often outperforming its predecessor, the GeForce 6800 Ultra, by a factor of two.

The GeForce 7800 GTX 512MB

Another shot of the 7800 GTX 512MB reference board

7800 GTX 512MB (top) ATI X1800 XT 512MB (bottom)

High-end shootout, two 7800 GTX boards vs X1800 XT 512MB

To do this, NVIDIA incorporated a number of improvements into G70 designed to boost performance. G70s vertex shaders were enhanced to speed up geometry processing, while tweaks were made in both the pixel and vertex shaders that made both units better at handling multiply-add (MADD) math operations. These computations are commonly used for lighting (for example, in effects like refraction and reflection, or embossing), normal map calculations (adding depth and height via normal maps to what are actually flat objects), and many other operations.

According to NVIDIA, the enhancements they’ve integrated into G70 increase pipeline efficiency by 50% on a clock-for-clock basis, while the tweaks made to the vertex shading units have sped up triangle setup by over 30%. NVIDIA also improved texture fetching and cut cycles in gamma adjusted rotated grid AA by a similar margin.

The most notable aspect of G70 though was arguably the increased number of pixel and vertex shaders.



NVIDIA integrated 24 pixel pipelines into the GeForce 7800 GTX’s G70 core - eight more pipes than any other previous architecture - while on the vertex processing side, eight units were incorporated into the 7800 GTX, that’s two more vertex units than the six found in the GeForce 6800 Ultra’s NV40 core. When combined with the GeForce 7800 GTX’s high clock speeds, 430MHz on the graphics core and 600MHz on the memory (1.2GHz effective), the GeForce 7800 GTX was without equal, nothing else on the market came close to delivering the features and performance of the GeForce 7800 GTX.

NVIDIA then followed the GeForce 7800 GTX up with another G70-based product, the less expensive GeForce 7800 GT.

The GeForce 7800 GT featured all the innovations found in GeForce 7800 GTX, only the number of pixel and vertex pipelines had been reduced to 20 and 7 respectively. NVIDIA also turned down the clock speeds to 400MHz on the G70 graphics core and 500MHz on the memory (1.0GHz effective). The result was a product that ran 10-20% slower than the GeForce 7800 GTX, but sold for over $100 less than the 7800 GTX, making it more appealing to a larger audience. NVIDIA and their board partners have even partnered with Activision to bundle a copy of Call of Duty 2 with the GeForce 7800 GT for a limited time on select cards, making the GeForce 7800 GT an even more tempting purchase.

After months of delays, ATI finally responded with the RADEON X1800 family, including the RADEON X1800 XT and X1800 XL. Early benchmark results gave the edge to ATI in D3D applications, while NVIDIA reigned supreme in OpenGL titles like DOOM 3. Since then however ATI has released a newer driver that delivers substantially improved OpenGL performance for the X1800 series, in our Quake 4 High-End Graphics Shootout article the RADEON X1800 XT 512MB actually outran NVIDIA’s flagship GeForce 7800 GTX.

The G70s: 7800 GT (top) 7800 GTX 512MB (middle) and 7800 GTX 256MB (bottom)

Another shot of the 512MB reference board

To combat this new threat, NVIDIA has commissioned their third graphics product using the proven G70 GPU, the GeForce 7800 GTX 512MB! With significantly boosted clocks and 512MB of GDDR3 memory onboard, the 7800 GTX 512MB is designed to do battle specifically with the RADEON X1800 XT 512MB. Let’s see how this new card performs shall we?