Radeon HD 4870 X2 vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which makes use of a 40 nm design. AMD has clocked the core frequency at 840 MHz. The GDDR5 RAM runs at a speed of 1050 MHz on this card. It features 800 SPUs along with 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 4870 X2		350 Watts
	Difference: 200 Watts (133%)

Memory Bandwidth

In theory, the Radeon HD 4870 X2 should be much faster than the Radeon HD 6790 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6790		134400 MB/sec
	Difference: 96000 (71%)

Texel Rate

The Radeon HD 4870 X2 is quite a bit (approximately 79%) more effective at anisotropic filtering than the Radeon HD 6790. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6790		33600 Mtexels/sec
	Difference: 26400 (79%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 4870 X2 is the winner, and very much so. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 6790		13440 Mpixels/sec
	Difference: 10560 (79%)

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 data (measured in megabytes per second) that can be moved over the external memory interface within a second. It's worked out by multiplying the interface width by its memory clock speed. If it uses DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the clock speed of the card. 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 also depends on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.