Radeon HD 4790 vs Radeon HD 7990

Intro

Compare those specifications to the Radeon HD 7990, which features core speeds of 950 MHz on the GPU, and 1500 MHz on the 3072 MB of GDDR5 memory. It features 2048 SPUs along with 128 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 7990 should theoretically be much superior to the Radeon HD 4790 overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 473600 (463%)

Texel Rate

The Radeon HD 7990 is much (more or less 1167%) better at AF than the Radeon HD 4790. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 224000 (1167%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7990 is the winner, by far. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 51200 (533%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of information (measured in MB per second) that can be transferred over the external memory interface within a second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type 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 anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This is worked out 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 graphics 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 could possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.