Radeon HD 3870 X2 1GB vs Radeon HD 6870

Intro

Compare those specs to the Radeon HD 6870, which has a core clock speed of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also uses a 256-bit memory bus, and makes use of a 40 nm design. It is comprised of 1120 SPUs, 56 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 3870 X2 1GB should theoretically perform a bit faster than the Radeon HD 6870 overall. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 6870		134400 MB/sec
	Difference: 9728 (7%)

Texel Rate

The Radeon HD 6870 should be a lot (about 91%) more effective at texture filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 24000 (91%)

Pixel Rate

The Radeon HD 6870 should be just a bit (about 9%) more effective at anti-aliasing than the Radeon HD 3870 X2 1GB, and also will be able to handle higher screen resolutions while still performing well. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 3870 X2 1GB		26400 Mpixels/sec
	Difference: 2400 (9%)

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 largest amount of information (counted in megabytes per second) that can be transferred past the external memory interface in a second. The number is calculated by multiplying the card's interface width by its memory speed. If it uses DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better 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 texture map elements (texels) that can be applied per second. This is calculated by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core 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 rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.