Radeon HD 4850 X2 512MB vs Radeon HD 6870

Intro

Compare all of that to the Radeon HD 6870, which comes with GPU clock speed of 900 MHz, and 1024 MB of GDDR5 memory running at 1050 MHz through a 256-bit bus. It also features 1120 SPUs, 56 Texture Address Units, and 32 ROPs.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6870		151 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 99 Watts (66%)

Memory Bandwidth

In theory, the Radeon HD 6870 should be just a bit faster than the Radeon HD 4850 X2 512MB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 7296 (6%)

Texel Rate

The Radeon HD 6870 will be a little bit (approximately 1%) better at anisotropic filtering than the Radeon HD 4850 X2 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4850 X2 512MB		50000 Mtexels/sec
	Difference: 400 (1%)

Pixel Rate

The Radeon HD 6870 is quite a bit (approximately 44%) better at AA than the Radeon HD 4850 X2 512MB, and also capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4850 X2 512MB		20000 Mpixels/sec
	Difference: 8800 (44%)

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 max amount of information (measured in MB per second) that can be transported over the external memory interface in a second. The number is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also called 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 bandwidth is, the lower the ability to reach the maximum fill rate.