Radeon HD 4870 2GB vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which features GPU core speed of 775 MHz, and 1024 MB of GDDR5 memory set to run at 1000 MHz through a 256-bit bus. It also is comprised of 960 SPUs, 48 TAUs, 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 2GB		150 Watts
	Difference: 23 Watts (18%)

Memory Bandwidth

Performance-wise, the Radeon HD 6850 should theoretically be just a bit better than the Radeon HD 4870 2GB overall. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The Radeon HD 6850 is quite a bit (more or less 24%) faster with regards to texture filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 7200 (24%)

Pixel Rate

The Radeon HD 6850 will be quite a bit (about 107%) faster with regards to full screen anti-aliasing than the Radeon HD 4870 2GB, and should be capable of handling higher screen resolutions better. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4870 2GB		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 maximum amount of data (counted in megabytes per second) that can be transported over the external memory interface in one second. It is worked out by multiplying the card's bus width by its memory speed. In the case of DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.