Radeon HD 4850 X2 512MB vs Radeon HD 6850

Intro

Compare all that to the Radeon HD 6850, which makes use of a 40 nm design. AMD has clocked the core speed at 775 MHz. The GDDR5 memory runs at a frequency of 1000 MHz on this specific card. It features 960 SPUs along with 48 Texture Address Units and 32 ROPs.

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

In theory, the Radeon HD 6850 is 1% quicker than the Radeon HD 4850 X2 512MB overall, due to its greater data rate. (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 is much (approximately 34%) faster with regards to 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 a lot (more or less 24%) better at anti-aliasing than the Radeon HD 4850 X2 512MB, and also should be capable of handling higher resolutions without losing too much performance. (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: Bandwidth is the maximum amount of data (counted in megabytes per second) that can be transported past the external memory interface in a second. It is calculated by multiplying the card's interface width by its memory speed. If it uses DDR memory, it must 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 high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.