Radeon HD 4870 2GB vs Radeon HD 7950 3GB

Intro

Compare all of that to the Radeon HD 7950 3GB, which makes use of a 28 nm design. AMD has set the core speed at 800 MHz. The GDDR5 RAM runs at a frequency of 1250 MHz on this 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 4870 2GB		150 Watts
Radeon HD 7950 3GB		200 Watts
	Difference: 50 Watts (33%)

Memory Bandwidth

The Radeon HD 7950 3GB should theoretically be much faster than the Radeon HD 4870 2GB overall. (explain)

Radeon HD 7950 3GB		240000 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 124800 (108%)

Texel Rate

The Radeon HD 7950 3GB will be quite a bit (approximately 199%) better at anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 7950 3GB		89600 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 59600 (199%)

Pixel Rate

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

Radeon HD 7950 3GB		25600 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 13600 (113%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of information (in units of MB per second) that can be transported over the external memory interface within a second. It's calculated by multiplying the interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better 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 processed per second. This is calculated by multiplying the total number of texture units by the core speed of the chip. The better the texel rate, the better the video 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 the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.