Radeon HD 3870 X2 1GB vs Radeon HD 6870

Intro

Compare all of that to the Radeon HD 6870, which uses a 40 nm design. AMD has clocked the core speed at 900 MHz. The GDDR5 RAM works at a frequency of 1050 MHz on this card. It features 1120 SPUs along with 56 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 3870 X2 1GB should theoretically be a small bit faster than the Radeon HD 6870 in general. (explain)

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

Texel Rate

The Radeon HD 6870 will be a lot (approximately 91%) more effective at AF 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 is just a bit (about 9%) more effective at anti-aliasing than the Radeon HD 3870 X2 1GB, and 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: Memory bandwidth is the largest amount of information (measured in megabytes per second) that can be transported across the external memory interface in a second. It's calculated by multiplying the card's interface width by the speed of its memory. 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 higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.