Radeon HD 4790 vs Radeon HD 6850

Intro

Compare those specifications to the Radeon HD 6850, which comes with 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

Theoretically speaking, the Radeon HD 6850 should perform 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 is a lot (more or less 94%) more effective at anisotropic filtering than the Radeon HD 4790. (explain)

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

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 6850 is superior to the Radeon HD 4790, 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: Memory bandwidth is the max amount of data (in units of MB per second) that can be transported over the external memory interface within a second. It is worked out by multiplying the bus width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This is worked out by multiplying the total texture units of the card by the core 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 the video card could possibly write to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.