Radeon HD 4850 2GB vs Radeon HD 6870

Intro

Compare those specifications to the Radeon HD 6870, which has a clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also makes use of a 256-bit bus, and uses a 40 nm design. It features 1120 SPUs, 56 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 2GB		110 Watts
Radeon HD 6870		151 Watts
	Difference: 41 Watts (37%)

Memory Bandwidth

As far as performance goes, the Radeon HD 6870 should in theory be a lot superior to the Radeon HD 4850 2GB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 70848 (111%)

Texel Rate

The Radeon HD 6870 will be much (more or less 102%) more effective at AF than the Radeon HD 4850 2GB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 25400 (102%)

Pixel Rate

The Radeon HD 6870 should be much (approximately 188%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 2GB, and also will be able to handle higher resolutions better. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4850 2GB		10000 Mpixels/sec
	Difference: 18800 (188%)

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 data (counted in MB per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total texture units of the card by the core clock 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 most pixels that the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.