Radeon HD 4870 512MB vs Radeon HD 4870 X2

Intro

Compare those specifications to the Radeon HD 4870 X2, which makes use of a 55 nm design. AMD has clocked the core speed at 750 MHz. The GDDR5 RAM works at a speed of 900 MHz on this specific card. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 512MB		150 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 200 Watts (133%)

Memory Bandwidth

In theory, the Radeon HD 4870 X2 is 100% quicker than the Radeon HD 4870 512MB overall, due to its higher bandwidth. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 115200 (100%)

Texel Rate

The Radeon HD 4870 X2 will be much (about 100%) better at anisotropic filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 30000 (100%)

Pixel Rate

The Radeon HD 4870 X2 will be much (approximately 100%) better at anti-aliasing than the Radeon HD 4870 512MB, and also should be capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 12000 (100%)

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 (in units of megabytes per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the card's bus width by its memory speed. If the card has DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the 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 texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total texture units by the core speed of the chip. The better this number, the better the video 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 amount of pixels the video card can possibly record to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.