Radeon HD 4790 vs Radeon HD 7770

Intro

Compare that to the Radeon HD 7770, which features a clock speed of 1000 MHz and a GDDR5 memory speed of 1125 MHz. It also features a 128-bit bus, and makes use of a 28 nm design. It is made up of 640 SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 4790 should theoretically be much superior to the Radeon HD 7770 in general. (explain)

Radeon HD 4790		102400 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 30400 (42%)

Texel Rate

The Radeon HD 7770 is much (approximately 108%) better at texture filtering than the Radeon HD 4790. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 20800 (108%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 7770 is the winner, and very much so. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 6400 (67%)

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 maximum amount of information (in units of MB per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This is calculated 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 processed in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few 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.