Radeon HD 4870 1GB vs Radeon HD 7950

Intro

Compare all that to the Radeon HD 7950, which features a clock frequency of 800 MHz and a GDDR5 memory frequency of 1250 MHz. It also makes use of a 384-bit bus, and uses a 28 nm design. It is comprised of 1792 SPUs, 112 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 1GB		150 Watts
Radeon HD 7950		200 Watts
	Difference: 50 Watts (33%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7950 is 108% faster than the Radeon HD 4870 1GB overall, due to its higher bandwidth. (explain)

Radeon HD 7950		240000 MB/sec
Radeon HD 4870 1GB		115200 MB/sec
	Difference: 124800 (108%)

Texel Rate

The Radeon HD 7950 should be quite a bit (about 199%) more effective at anisotropic filtering than the Radeon HD 4870 1GB. (explain)

Radeon HD 7950		89600 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 59600 (199%)

Pixel Rate

The Radeon HD 7950 will be quite a bit (approximately 113%) better at anti-aliasing than the Radeon HD 4870 1GB, and also should be able to handle higher screen resolutions without slowing down too much. (explain)

Radeon HD 7950		25600 Mpixels/sec
Radeon HD 4870 1GB		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 MB per second) that can be transferred past the external memory interface in a second. It's worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed per second. This figure is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the most pixels 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 Raster Operations Pipelines 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 fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.