Radeon HD 4850 X2 512MB vs Radeon HD 6790

Intro

Compare that to the Radeon HD 6790, which uses a 40 nm design. AMD has set the core speed at 840 MHz. The GDDR5 memory is set to run at a frequency of 1050 MHz on this specific model. 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 512MB		250 Watts
	Difference: 100 Watts (67%)

Memory Bandwidth

In theory, the Radeon HD 6790 will be 6% faster than the Radeon HD 4850 X2 512MB in general, because of its higher data rate. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 7296 (6%)

Texel Rate

The Radeon HD 4850 X2 512MB is quite a bit (approximately 49%) faster with regards to texture filtering than the Radeon HD 6790. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 6790		33600 Mtexels/sec
	Difference: 16400 (49%)

Pixel Rate

The Radeon HD 4850 X2 512MB should be much (more or less 49%) more effective at AA than the Radeon HD 6790, and also capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 4850 X2 512MB		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: Memory bandwidth is the max amount of information (in units of MB per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the card's interface width by its memory speed. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.