Radeon HD 3870 X2 512MB vs Radeon HD 4790

Intro

Compare those specs to the Radeon HD 4790, which has a core clock frequency of 600 MHz and a GDDR5 memory frequency of 800 MHz. It also makes use of a 256-bit memory bus, and makes use of a 55 nm design. It features 640(128x5) SPUs, 32 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 X2 512MB is 13% faster than the Radeon HD 4790 in general, due to its higher data rate. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 12800 (13%)

Texel Rate

The Radeon HD 3870 X2 512MB should be much (more or less 38%) faster with regards to anisotropic filtering than the Radeon HD 4790. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 7200 (38%)

Pixel Rate

The Radeon HD 3870 X2 512MB is much (approximately 175%) more effective at FSAA than the Radeon HD 4790, and capable of handling higher resolutions more effectively. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 16800 (175%)

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 largest amount of information (counted in MB per second) that can be transferred over the external memory interface in one second. It is worked out by multiplying the bus width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, 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 texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.