GeForce 8800 GTS (G80) 640MB vs Radeon HD 4870 512MB

Intro

Compare those specs to the Radeon HD 4870 512MB, which comes with a GPU core clock speed of 750 MHz, and 512 MB of GDDR5 memory set to run at 900 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8800 GTS (G80) 640MB		143 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 7 Watts (5%)

Memory Bandwidth

In theory, the Radeon HD 4870 512MB will be 82% faster than the GeForce 8800 GTS (G80) 640MB in general, because of its higher bandwidth. (explain)

Radeon HD 4870 512MB		115200 MB/sec
GeForce 8800 GTS (G80) 640MB		63360 MB/sec
	Difference: 51840 (82%)

Texel Rate

The Radeon HD 4870 512MB is quite a bit (about 22%) better at AF than the GeForce 8800 GTS (G80) 640MB. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
GeForce 8800 GTS (G80) 640MB		24624 Mtexels/sec
	Difference: 5376 (22%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 4870 512MB is the winner, though not by far. (explain)

Radeon HD 4870 512MB		12000 Mpixels/sec
GeForce 8800 GTS (G80) 640MB		10260 Mpixels/sec
	Difference: 1740 (17%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of data (measured in MB per second) that can be transported past the external memory interface in a second. The number is worked out by multiplying the interface width by the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied in one second. This number is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.