Radeon HD 4890 1GB vs Radeon HD 7950 3GB

Intro

Compare all of that to the Radeon HD 7950 3GB, which comes with GPU core speed of 800 MHz, and 3072 MB of GDDR5 memory running at 1250 MHz through a 384-bit bus. It also is comprised of 1792 SPUs, 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 3GB		200 Watts
	Difference: 10 Watts (5%)

Memory Bandwidth

In theory, the Radeon HD 7950 3GB will be 92% faster than the Radeon HD 4890 1GB in general, because of its greater data rate. (explain)

Radeon HD 7950 3GB		240000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 115200 (92%)

Texel Rate

The Radeon HD 7950 3GB should be quite a bit (more or less 124%) better at anisotropic filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7950 3GB		89600 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 49600 (124%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7950 3GB is a better choice, by a large margin. (explain)

Radeon HD 7950 3GB		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 max amount of information (measured in MB per second) that can be transported past the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster 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 amount of texture map elements (texels) that can be applied per second. This 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 video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.