Radeon HD 4770 vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which has a core clock speed of 840 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 256-bit bus, and makes use of a 40 nm design. It is made up of 800 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4770		80 Watts
Radeon HD 6790		150 Watts
	Difference: 70 Watts (88%)

Memory Bandwidth

In theory, the Radeon HD 6790 should be a lot faster than the Radeon HD 4770 in general. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 83200 (163%)

Texel Rate

The Radeon HD 6790 will be quite a bit (about 40%) faster with regards to anisotropic filtering than the Radeon HD 4770. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 9600 (40%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6790 is the winner, not by a very large margin though. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4770		12000 Mpixels/sec
	Difference: 1440 (12%)

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 data (in units of megabytes per second) that can be transferred past the external memory interface in one second. It's worked out by multiplying the card's interface width by its memory clock speed. If it uses DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

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