Radeon HD 4790 vs Radeon HD 6850

Intro

Compare those specifications to the Radeon HD 6850, which has a core clock frequency of 775 MHz and a GDDR5 memory frequency of 1000 MHz. It also uses a 256-bit memory bus, and makes use of 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 in theory perform quite a bit 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

If using high levels of AA is important to you, then the Radeon HD 6850 is a better choice, by far. (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 information (counted in MB per second) that can be moved over the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This is worked out by multiplying the total texture units by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

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