GeForce 8800 GTS (G80) 640MB vs Radeon HD 3870 512MB

Intro

Compare all of that to the Radeon HD 3870 512MB, which features a core clock speed of 775 MHz and a GDDR3 memory speed of 900 MHz. It also uses a 256-bit memory bus, and makes use of a 55 nm design. It is made up of 320(64x5) SPUs, 16 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 512MB		106 Watts
GeForce 8800 GTS (G80) 640MB		143 Watts
	Difference: 37 Watts (35%)

Memory Bandwidth

In theory, the GeForce 8800 GTS (G80) 640MB will be 10% faster than the Radeon HD 3870 512MB in general, because of its higher bandwidth. (explain)

GeForce 8800 GTS (G80) 640MB		63360 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 5760 (10%)

Texel Rate

The GeForce 8800 GTS (G80) 640MB is a lot (about 99%) more effective at AF than the Radeon HD 3870 512MB. (explain)

GeForce 8800 GTS (G80) 640MB		24624 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 12224 (99%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 3870 512MB is superior to the GeForce 8800 GTS (G80) 640MB, by far. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
GeForce 8800 GTS (G80) 640MB		10260 Mpixels/sec
	Difference: 2140 (21%)

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 information (in units of MB per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory speed. If it uses DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.