Radeon HD 4890 1GB vs Radeon HD 7950

Intro

Compare all that to the Radeon HD 7950, which has clock speeds of 800 MHz on the GPU, and 1250 MHz on the 1536 MB of GDDR5 RAM. It features 1792 SPUs as well as 112 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 1GB		190 Watts
Radeon HD 7950		200 Watts
	Difference: 10 Watts (5%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7950 should be 92% faster than the Radeon HD 4890 1GB in general, due to its higher data rate. (explain)

Radeon HD 7950		240000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 115200 (92%)

Texel Rate

The Radeon HD 7950 should be a lot (approximately 124%) more effective at texture filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7950		89600 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 49600 (124%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 7950 is a better choice, by far. (explain)

Radeon HD 7950		25600 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 9600 (60%)

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 (counted in megabytes per second) that can be transferred over the external memory interface in one second. It is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, it should be multiplied by 2 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 AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the graphics 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 per 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 - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.