Radeon HD 4890 1GB vs Radeon HD 7970

Intro

Compare those specifications to the Radeon HD 7970, which makes use of a 28 nm design. AMD has set the core frequency at 925 MHz. The GDDR5 RAM is set to run at a frequency of 1375 MHz on this specific card. It features 2048 SPUs as well as 128 Texture Address Units 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 7970		250 Watts
	Difference: 60 Watts (32%)

Memory Bandwidth

In theory, the Radeon HD 7970 should be 112% faster than the Radeon HD 4890 1GB overall, because of its higher data rate. (explain)

Radeon HD 7970		264000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 139200 (112%)

Texel Rate

The Radeon HD 7970 is quite a bit (about 196%) more effective at texture filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7970		118400 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 78400 (196%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 7970 is the winner, and very much so. (explain)

Radeon HD 7970		29600 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 13600 (85%)

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: Bandwidth is the maximum amount of data (measured in megabytes per second) that can be transported across the external memory interface within a second. The number is worked out by multiplying the card's interface width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.