OC: Radeon HD2900XT 512 MB vs GeForce 8800GTS 640 MB - 8800GTS 640
Author: Luka Rakamaric
Date: 26 Jun 2007

Its main competitor, the 8800GTS 640 is based on a G80 GPU, which is also very close to 700 million transistors. Such a chip is expected to produce a similar amount of heat, at least on the same clock and voltage. However, the operating frequency of the G80 in a GTS card is ?only? 500 MHz, or only two thirds of the R600. The cooler is pretty much the same, but use of aluminum suggests that NVIDIA has a lot less heat output. The low core clock also promises more OC capabilities, although chips made in 90 nm production process can?t go as high as those in 80 like the R600.

It is interesting to notice that these two cards, when clocked at stock speeds, produce quite similar results. The lack of performance gain from high core clocks the 8800GTS makes up in more shaders, 96 compared to ?64? of the R600. So the R600 has 2/3 of the shaders of G80, and the G80 has around 2/3 of the clock of the R600, which obviously cancels each other out.

To benchmark the cards we assembled our usual testbed for graphics cards:

- Intel Core 2 Duo E6700
- EVGA 680i SLI
- OCZ PC2-8000 @ 800MHz 4-4-4-12
- Western Digital RaptorX 150 GB
- OCZ GameXStream 1010W