Radeon HD 4870 X2 vs Radeon HD 5850

Intro

Compare all that to the Radeon HD 5850, which has GPU clock speed of 725 MHz, and 1024 MB of GDDR5 RAM running at 1000 MHz through a 256-bit bus. It also is comprised of 1440(288x5) SPUs, 72 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 5850		151 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 199 Watts (132%)

Memory Bandwidth

In theory, the Radeon HD 4870 X2 should be quite a bit faster than the Radeon HD 5850 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 5850		128000 MB/sec
	Difference: 102400 (80%)

Texel Rate

The Radeon HD 4870 X2 should be a small bit (more or less 15%) better at AF than the Radeon HD 5850. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 5850		52200 Mtexels/sec
	Difference: 7800 (15%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 4870 X2 is a better choice, not by a very large margin though. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 5850		23200 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 largest amount of information (in units of megabytes per second) that can be moved across the external memory interface within a second. The number is calculated by multiplying the card's bus width by its memory speed. If it uses DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, 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 are applied per second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher 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 most pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.