Radeon HD 4790 vs Radeon HD 7790

Intro

Compare those specifications to the Radeon HD 7790, which makes use of a 28 nm design. AMD has clocked the core frequency at 1000 MHz. The GDDR5 memory runs at a speed of 1500 MHz on this specific card. It features 896 SPUs along with 56 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 4790 will be 7% faster than the Radeon HD 7790 in general, due to its greater data rate. (explain)

Radeon HD 4790		102400 MB/sec
Radeon HD 7790		96000 MB/sec
	Difference: 6400 (7%)

Texel Rate

The Radeon HD 7790 is quite a bit (approximately 192%) better at AF than the Radeon HD 4790. (explain)

Radeon HD 7790		56000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 36800 (192%)

Pixel Rate

The Radeon HD 7790 should be a lot (approximately 67%) more effective at FSAA than the Radeon HD 4790, and will be able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 7790		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 (counted in megabytes per second) that can be transferred over the external memory interface in a second. It is worked out by multiplying the card's interface width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core 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 many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.