Radeon HD 4890 2GB vs Radeon HD 7970

Intro

Compare that to the Radeon HD 7970, which features a clock frequency of 925 MHz and a GDDR5 memory frequency of 1375 MHz. It also uses a 384-bit memory bus, and uses a 28 nm design. It features 2048 SPUs, 128 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 4890 2GB		190 Watts
Radeon HD 7970		250 Watts
	Difference: 60 Watts (32%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7970 should be 112% quicker than the Radeon HD 4890 2GB overall, because of its higher data rate. (explain)

Radeon HD 7970		264000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 139200 (112%)

Texel Rate

The Radeon HD 7970 should be much (more or less 196%) faster with regards to AF than the Radeon HD 4890 2GB. (explain)

Radeon HD 7970		118400 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 78400 (196%)

Pixel Rate

The Radeon HD 7970 will be a lot (about 85%) better at FSAA than the Radeon HD 4890 2GB, and also will be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 7970		29600 Mpixels/sec
Radeon HD 4890 2GB		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 max amount of data (counted in MB per second) that can be moved across the external memory interface within a second. The number is calculated 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 ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is worked out 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 handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.