Radeon HD 4790 vs Radeon HD 6770 1GB

Intro

Compare all that to the Radeon HD 6770 1GB, which has GPU clock speed of 900 MHz, and 1024 MB of GDDR5 memory set to run at 1050 MHz through a 128-bit bus. It also is comprised of 800 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 4790 should in theory be quite a bit faster than the Radeon HD 6770 1GB overall. (explain)

Radeon HD 4790		102400 MB/sec
Radeon HD 6770 1GB		67200 MB/sec
	Difference: 35200 (52%)

Texel Rate

The Radeon HD 6770 1GB is a lot (more or less 88%) better at anisotropic filtering than the Radeon HD 4790. (explain)

Radeon HD 6770 1GB		36000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 16800 (88%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 6770 1GB is superior to the Radeon HD 4790, by far. (explain)

Radeon HD 6770 1GB		14400 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 4800 (50%)

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 information (counted in MB per second) that can be moved past the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better 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 applied in one second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.