Radeon HD 4850 512MB vs Radeon HD 6870

Intro

Compare those specs to the Radeon HD 6870, which comes with a core clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 256-bit memory bus, and uses a 40 nm design. It features 1120 SPUs, 56 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 4850 512MB		110 Watts
Radeon HD 6870		151 Watts
	Difference: 41 Watts (37%)

Memory Bandwidth

In theory, the Radeon HD 6870 should be quite a bit faster than the Radeon HD 4850 512MB overall. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 70848 (111%)

Texel Rate

The Radeon HD 6870 should be much (approximately 102%) faster with regards to anisotropic filtering than the Radeon HD 4850 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 25400 (102%)

Pixel Rate

The Radeon HD 6870 will be quite a bit (about 188%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 512MB, and also will be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4850 512MB		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: Bandwidth is the max amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. It is calculated by multiplying the bus width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units 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 fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.