Radeon HD 4870 512MB vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which uses a 40 nm design. AMD has set the core speed at 775 MHz. The GDDR5 RAM works at a speed of 1000 MHz on this model. It features 960 SPUs as well as 48 TAUs and 32 Rasterization Operator 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

The Radeon HD 6850 should theoretically perform 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 will be much (more or less 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 using a high resolution is important to you, then the Radeon HD 6850 is the winner, and very much so. (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: Memory bandwidth is the largest amount of information (counted in MB per second) that can be transported across the external memory interface in a second. It is worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total number of 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 applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.