Radeon HD 4850 X2 1GB vs Radeon HD 6790

Intro

Compare those specifications 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 RAM. It features 800 SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6790		150 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 100 Watts (67%)

Memory Bandwidth

The Radeon HD 6790 should in theory perform a bit faster than the Radeon HD 4850 X2 1GB overall. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 7296 (6%)

Texel Rate

The Radeon HD 4850 X2 1GB will be quite a bit (more or less 49%) more effective at AF than the Radeon HD 6790. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 6790		33600 Mtexels/sec
	Difference: 16400 (49%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 4850 X2 1GB is a better choice, by far. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 6790		13440 Mpixels/sec
	Difference: 6560 (49%)

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 maximum amount of data (measured in MB per second) that can be transferred across the external memory interface in a second. It's calculated by multiplying the interface width by its memory clock speed. If it uses DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed in one second. This figure is worked out by multiplying the total number of texture units 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also 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, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.