Radeon HD 4870 X2 vs Radeon HD 7950

Intro

Compare those specifications to the Radeon HD 7950, which uses a 28 nm design. AMD has clocked the core frequency at 800 MHz. The GDDR5 memory works at a frequency of 1250 MHz on this particular model. It features 1792 SPUs along with 112 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

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

Memory Bandwidth

Performance-wise, the Radeon HD 7950 should theoretically be a little bit better than the Radeon HD 4870 X2 overall. (explain)

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

Texel Rate

The Radeon HD 7950 will be much (approximately 49%) faster with regards to AF than the Radeon HD 4870 X2. (explain)

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

Pixel Rate

The Radeon HD 7950 will be a small bit (more or less 7%) faster with regards to anti-aliasing than the Radeon HD 4870 X2, and capable of handling higher screen resolutions better. (explain)

Radeon HD 7950		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 max amount of information (in units of MB per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory clock speed. If the card has DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.