Radeon HD 4790 vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which comes with a GPU core clock speed of 840 MHz, and 1024 MB of GDDR5 RAM set to run at 1050 MHz through a 256-bit bus. It also is made up of 800 Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 6790 should theoretically be a lot superior to the Radeon HD 4790 in general. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 32000 (31%)

Texel Rate

The Radeon HD 6790 is a lot (about 75%) more effective at texture filtering than the Radeon HD 4790. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 14400 (75%)

Pixel Rate

The Radeon HD 6790 will be much (more or less 40%) faster with regards to anti-aliasing than the Radeon HD 4790, and capable of handling higher screen resolutions more effectively. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 3840 (40%)

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 data (in units of megabytes per second) that can be transported over the external memory interface in one second. It is worked out by multiplying the interface width by its memory speed. In the case of DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per 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 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 one second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.