Radeon HD 4770 vs Radeon HD 6790

Intro

Compare all of that to the Radeon HD 6790, which features a core clock frequency of 840 MHz and a GDDR5 memory frequency of 1050 MHz. It also makes use of a 256-bit memory bus, and uses 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

As far as performance goes, the Radeon HD 6790 should in theory be a lot superior to 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 is much (more or less 40%) better at AF than the Radeon HD 4770. (explain)

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

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 6790 is the winner, though not by far. (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: Memory bandwidth is the max amount of information (measured in megabytes per second) that can be transferred past the external memory interface in a second. The number is worked out by multiplying the interface width by its memory clock speed. If it uses DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, 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 applied in one second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the video 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 maximum amount of pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of 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 fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.