Radeon HD 4850 X2 1GB vs Radeon HD 6850

Intro

Compare those specifications to the Radeon HD 6850, which has a GPU core clock speed of 775 MHz, and 1024 MB of GDDR5 RAM set to run at 1000 MHz through a 256-bit bus. It also features 960 SPUs, 48 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 6850		127 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 123 Watts (97%)

Memory Bandwidth

Theoretically, the Radeon HD 6850 should be just a bit faster than the Radeon HD 4850 X2 1GB in general. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 896 (1%)

Texel Rate

The Radeon HD 4850 X2 1GB is quite a bit (about 34%) better at texture filtering than the Radeon HD 6850. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 6850		37200 Mtexels/sec
	Difference: 12800 (34%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 6850 is superior to the Radeon HD 4850 X2 1GB, by a large margin. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4850 X2 1GB		20000 Mpixels/sec
	Difference: 4800 (24%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of information (counted in MB per second) that can be transported across the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total number 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 processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.