Radeon HD 4870 X2 vs Radeon HD 7950 3GB

Intro

Compare those specs to the Radeon HD 7950 3GB, which comes with a core clock speed of 800 MHz and a GDDR5 memory frequency of 1250 MHz. It also makes use of a 384-bit memory bus, and makes use of a 28 nm design. It is made up of 1792 SPUs, 112 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7950 3GB		200 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 150 Watts (75%)

Memory Bandwidth

In theory, the Radeon HD 7950 3GB will be 4% faster than the Radeon HD 4870 X2 in general, due to its greater data rate. (explain)

Radeon HD 7950 3GB		240000 MB/sec
Radeon HD 4870 X2		230400 MB/sec
	Difference: 9600 (4%)

Texel Rate

The Radeon HD 7950 3GB is quite a bit (approximately 49%) faster with regards to texture filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 7950 3GB		89600 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 29600 (49%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 7950 3GB is the winner, though only just barely. (explain)

Radeon HD 7950 3GB		25600 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 1600 (7%)

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 MB per second) that can be moved over the external memory interface in one second. It is calculated by multiplying the interface width by its memory clock speed. In the case of DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write 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 core 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 output rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.