Radeon HD 4870 512MB vs Radeon HD 7950 3GB

Intro

Compare those specs to the Radeon HD 7950 3GB, which makes use of a 28 nm design. AMD has clocked the core frequency at 800 MHz. The GDDR5 memory is set to run at a speed 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 512MB		150 Watts
Radeon HD 7950 3GB		200 Watts
	Difference: 50 Watts (33%)

Memory Bandwidth

The Radeon HD 7950 3GB, in theory, should be a lot faster than the Radeon HD 4870 512MB overall. (explain)

Radeon HD 7950 3GB		240000 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 124800 (108%)

Texel Rate

The Radeon HD 7950 3GB should be quite a bit (approximately 199%) more effective at anisotropic filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 7950 3GB		89600 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 59600 (199%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 7950 3GB is superior to the Radeon HD 4870 512MB, by a large margin. (explain)

Radeon HD 7950 3GB		25600 Mpixels/sec
Radeon HD 4870 512MB		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: Bandwidth is the max amount of data (measured in MB per second) that can be transferred past the external memory interface in a second. The number is worked out by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the faster 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 can be processed in one second. This figure is calculated by multiplying the total amount of texture units of the card 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.