Radeon HD 4790 vs Radeon HD 6770

Intro

Compare all of that to the Radeon HD 6770, which comes with a clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 128-bit memory bus, and uses a 40 nm design. It features 800 SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 4790 should be quite a bit faster than the Radeon HD 6770 overall. (explain)

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

Texel Rate

The Radeon HD 6770 should be a lot (about 88%) more effective at texture filtering than the Radeon HD 4790. (explain)

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

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 6770 is a better choice, by far. (explain)

Radeon HD 6770		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: Memory bandwidth is the max amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. It's worked out by multiplying the interface width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's 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 in one second. This number is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the video card will be at 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 that the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.