Radeon HD 4870 X2 vs Radeon HD 7950 3GB

Intro

Compare those specs to the Radeon HD 7950 3GB, which has a clock speed of 800 MHz and a GDDR5 memory frequency of 1250 MHz. It also uses a 384-bit memory bus, and makes use of a 28 nm design. It is made up of 1792 SPUs, 112 Texture Address Units, and 32 ROPs.

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

As far as performance goes, the Radeon HD 7950 3GB should theoretically be a small bit better than the Radeon HD 4870 X2 overall. (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 should be quite a bit (more or less 49%) more effective at 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 using high levels of AA is important to you, then the Radeon HD 7950 3GB is the winner, though not by far. (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: Bandwidth is the maximum amount of information (measured in megabytes per second) that can be transported across the external memory interface in one second. It's worked out by multiplying the card's interface width by its memory clock speed. If the card has 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 amount of texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka 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 bandwidth is, the lower the potential to reach the maximum fill rate.