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 frequency 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 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

Theoretically speaking, the Radeon HD 6870 should be much faster than 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 should be a lot (about 102%) faster with regards to anisotropic filtering 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

If running with high levels of AA is important to you, then the Radeon HD 6870 is the winner, by a large margin. (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 (in units of MB per second) that can be transferred across the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If the card has DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. 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 amount of texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher 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 most pixels the video card could possibly record to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.