Radeon HD 4890 1GB 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 set the core frequency at 800 MHz. The GDDR5 RAM runs at a frequency of 1250 MHz on this specific model. It features 1792 SPUs along with 112 TAUs and 32 Rasterization Operator Units.

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

Theoretically speaking, the Radeon HD 7950 3GB will be 92% quicker than the Radeon HD 4890 1GB overall, 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 will be a lot (more or less 124%) faster with regards to AF 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

The Radeon HD 7950 3GB should be quite a bit (more or less 60%) faster with regards to FSAA than the Radeon HD 4890 1GB, and also able to handle higher screen resolutions without losing too much performance. (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 maximum amount of information (counted in MB per second) that can be transported past the external memory interface within a second. It is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to the 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 clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.