GeForce GTX 660 vs Radeon HD 3870 X2 512MB

Intro

Compare those specs to the Radeon HD 3870 X2 512MB, which has a clock frequency of 825 MHz and a GDDR3 memory frequency of 900 MHz. It also makes use of a 256-bit bus, and uses a 55 nm design. It is comprised of 320(64x5) SPUs, 16 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the GeForce GTX 660 will be 25% quicker than the Radeon HD 3870 X2 512MB overall, because of its greater bandwidth. (explain)

GeForce GTX 660		144192 MB/sec
Radeon HD 3870 X2 512MB		115200 MB/sec
	Difference: 28992 (25%)

Texel Rate

The GeForce GTX 660 should be quite a bit (about 197%) better at anisotropic filtering than the Radeon HD 3870 X2 512MB. (explain)

GeForce GTX 660		78400 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 52000 (197%)

Pixel Rate

The Radeon HD 3870 X2 512MB will be a small bit (more or less 12%) better at full screen anti-aliasing than the GeForce GTX 660, and able to handle higher resolutions better. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
GeForce GTX 660		23520 Mpixels/sec
	Difference: 2880 (12%)

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 max amount of information (measured in megabytes per second) that can be moved over the external memory interface in one second. The number is worked out by multiplying the interface width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total number of texture units of the card by the core clock 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 in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated 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 filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.