Radeon HD 4870 512MB vs Radeon HD 6850

Intro

Compare that to the Radeon HD 6850, which comes with a GPU core clock speed of 775 MHz, and 1024 MB of GDDR5 memory running at 1000 MHz through a 256-bit bus. It also features 960 Stream Processors, 48 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850		127 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 23 Watts (18%)

Memory Bandwidth

Theoretically, the Radeon HD 6850 should be just a bit faster than the Radeon HD 4870 512MB in general. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The Radeon HD 6850 should be much (about 24%) more effective at texture filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 7200 (24%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 6850 is superior to the Radeon HD 4870 512MB, by far. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 12800 (107%)

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: Bandwidth is the max amount of information (measured in megabytes per second) that can be moved past the external memory interface within a second. The number is calculated by multiplying the card's interface width by its memory speed. If it uses DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.