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

Intro

Compare that to the Radeon HD 4870 512MB, which comes with GPU clock speed of 750 MHz, and 512 MB of GDDR5 memory set to run at 900 MHz through a 256-bit bus. It also is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

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

Performance-wise, the Radeon HD 4870 512MB should theoretically be a lot better than the GeForce 8800 GTS (G80) 640MB in general. (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 should be much (more or less 22%) more effective 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

The Radeon HD 4870 512MB is a little bit (more or less 17%) more effective at anti-aliasing than the GeForce 8800 GTS (G80) 640MB, and should be capable of handling higher resolutions without slowing down too much. (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 largest amount of information (counted in megabytes per second) that can be transferred across the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better 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 number of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.