Radeon HD 4890 1GB vs Radeon HD 7790

Intro

Compare those specs to the Radeon HD 7790, which features clock speeds of 1000 MHz on the GPU, and 1500 MHz on the 1024 MB of GDDR5 memory. It features 896 SPUs along with 56 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7790		85 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 105 Watts (124%)

Memory Bandwidth

As far as performance goes, the Radeon HD 4890 1GB should in theory be a lot better than the Radeon HD 7790 in general. (explain)

Radeon HD 4890 1GB		124800 MB/sec
Radeon HD 7790		96000 MB/sec
	Difference: 28800 (30%)

Texel Rate

The Radeon HD 7790 should be much (approximately 40%) more effective at anisotropic filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7790		56000 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 16000 (40%)

Pixel Rate

Both cards have the exact same pixel fill rate, so in theory they should perform equally good at at AA, and be able to handle the same screen resolutions. (explain)

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 (measured in MB per second) that can be transported across the external memory interface within a second. The number is calculated by multiplying the bus width by the speed of its memory. In the case of DDR type memory, it must 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 AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.