Radeon HD 4870 512MB vs Radeon HD 7950 3GB

Intro

Compare those specifications 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

Hide Graphs

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

In theory, the Radeon HD 7950 3GB will be 108% faster than the Radeon HD 4870 512MB overall, because of its higher bandwidth. (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 will be quite a bit (about 199%) faster with regards to texture 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 running with a high screen resolution is important to you, then the Radeon HD 7950 3GB is the winner, 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: Memory bandwidth is the largest amount of data (counted in megabytes per second) that can be transferred past the external memory interface in a second. It's calculated by multiplying the card's bus width by its memory speed. If it uses DDR type 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 better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock 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 in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could 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 ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.