Radeon HD 4870 2GB vs Radeon HD 6850

Intro

Compare those specs 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 is comprised of 960 Stream Processors, 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

As far as performance goes, the Radeon HD 6850 should in theory be just a bit superior to 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 should be a lot (about 24%) better at anisotropic 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 should be quite a bit (more or less 107%) better at full screen anti-aliasing than the Radeon HD 4870 2GB, and should be able to handle higher screen resolutions without losing too much performance. (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 information (measured in MB per second) that can be transferred over the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory speed. If the card has DDR RAM, 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, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.