Radeon HD 4850 X2 512MB vs Radeon HD 6850

Intro

Compare that to the Radeon HD 6850, which comes with clock speeds of 775 MHz on the GPU, and 1000 MHz on the 1024 MB of GDDR5 RAM. It features 960 SPUs along with 48 TAUs and 32 Rasterization Operator 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 512MB		250 Watts
	Difference: 123 Watts (97%)

Memory Bandwidth

The Radeon HD 6850 should in theory be just a bit faster than the Radeon HD 4850 X2 512MB in general. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 896 (1%)

Texel Rate

The Radeon HD 4850 X2 512MB will be quite a bit (more or less 34%) better at texture filtering than the Radeon HD 6850. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 6850		37200 Mtexels/sec
	Difference: 12800 (34%)

Pixel Rate

The Radeon HD 6850 should be quite a bit (about 24%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 X2 512MB, and will be capable of handling higher resolutions more effectively. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4850 X2 512MB		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 data (counted in megabytes per second) that can be moved past the external memory interface in a second. It is calculated by multiplying the bus width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory per 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 - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.