Radeon HD 4790 vs Radeon HD 6850

Intro

Compare that to the Radeon HD 6850, which features a core clock frequency of 775 MHz and a GDDR5 memory speed of 1000 MHz. It also uses a 256-bit bus, and uses a 40 nm design. It is comprised of 960 SPUs, 48 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 6850 should theoretically perform a lot faster than the Radeon HD 4790 overall. (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 (about 94%) better at AF than the Radeon HD 4790. (explain)

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

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 6850 is a better choice, by a large margin. (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: Bandwidth is the maximum amount of data (counted in MB per second) that can be moved over the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory speed. If it uses DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's 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 can be applied per second. This figure is calculated by multiplying the total texture units by the core clock speed of the chip. The higher 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 most pixels that the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the the core 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 also depends on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.