Radeon HD 4870 X2 vs Radeon HD 7970

Intro

Compare those specifications to the Radeon HD 7970, which features a core clock frequency of 925 MHz and a GDDR5 memory frequency of 1375 MHz. It also makes use of a 384-bit memory bus, and uses a 28 nm design. It is made up of 2048 SPUs, 128 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7970		250 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 100 Watts (40%)

Memory Bandwidth

Theoretically, the Radeon HD 7970 should perform a bit faster than the Radeon HD 4870 X2 in general. (explain)

Radeon HD 7970		264000 MB/sec
Radeon HD 4870 X2		230400 MB/sec
	Difference: 33600 (15%)

Texel Rate

The Radeon HD 7970 is much (more or less 97%) more effective at anisotropic filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 7970		118400 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 58400 (97%)

Pixel Rate

The Radeon HD 7970 should be quite a bit (about 23%) better at AA than the Radeon HD 4870 X2, and also should be able to handle higher screen resolutions better. (explain)

Radeon HD 7970		29600 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 5600 (23%)

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: Memory bandwidth is the largest amount of information (in units of megabytes per second) that can be transferred over the external memory interface in one second. It is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.