Radeon HD 4790 vs Radeon HD 6790

Intro

Compare all of that to the Radeon HD 6790, which comes with core clock speeds of 840 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 memory. It features 800 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 6790 will be 31% faster than the Radeon HD 4790 in general, due to its higher bandwidth. (explain)

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

Texel Rate

The Radeon HD 6790 should be much (more or less 75%) better at AF than the Radeon HD 4790. (explain)

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

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 6790 is superior to the Radeon HD 4790, and very much so. (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: Bandwidth is the maximum amount of information (in units of MB per second) that can be transferred across the external memory interface in one second. It's worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, 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 can be processed in one second. This number 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 applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.