Radeon HD 4790 vs Radeon HD 6850

Intro

Compare all of that to the Radeon HD 6850, which comes with GPU core speed of 775 MHz, and 1024 MB of GDDR5 memory running at 1000 MHz through a 256-bit bus. It also is made up of 960 SPUs, 48 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 6850 should in theory be much faster than the Radeon HD 4790 in general. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 25600 (25%)

Texel Rate

The Radeon HD 6850 should be much (approximately 94%) faster with regards to texture filtering than the Radeon HD 4790. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 18000 (94%)

Pixel Rate

The Radeon HD 6850 is much (about 158%) better at AA than the Radeon HD 4790, and also able to handle higher screen resolutions better. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 15200 (158%)

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 data (counted in MB per second) that can be transferred over the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.