Radeon HD 4870 X2 vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which comes with a core clock frequency of 775 MHz and a GDDR5 memory speed of 1000 MHz. It also makes use of a 256-bit memory bus, and makes use of a 40 nm design. It is made up of 960 SPUs, 48 Texture Address Units, and 32 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850		127 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 223 Watts (176%)

Memory Bandwidth

The Radeon HD 4870 X2 should in theory perform much faster than the Radeon HD 6850 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6850		128000 MB/sec
	Difference: 102400 (80%)

Texel Rate

The Radeon HD 4870 X2 will be much (approximately 61%) more effective at AF than the Radeon HD 6850. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6850		37200 Mtexels/sec
	Difference: 22800 (61%)

Pixel Rate

The Radeon HD 6850 should be just a bit (approximately 3%) more effective at full screen anti-aliasing than the Radeon HD 4870 X2, and will be able to handle higher screen resolutions more effectively. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 800 (3%)

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 data (measured in MB per second) that can be moved over the external memory interface in a second. It is calculated by multiplying the interface width by the speed of its memory. If the card has DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better 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 figure is calculated by multiplying the total number of texture units by the core speed of the chip. The higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount 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 lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.