Radeon HD 3870 X2 1GB vs Radeon HD 4870 X2

Intro

Compare those specs to the Radeon HD 4870 X2, which uses a 55 nm design. AMD has set the core speed at 750 MHz. The GDDR5 RAM works at a speed of 900 MHz on this specific card. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 is 60% faster than the Radeon HD 3870 X2 1GB overall, due to its higher data rate. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 86272 (60%)

Texel Rate

The Radeon HD 4870 X2 will be a lot (about 127%) faster with regards to AF than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 33600 (127%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 3870 X2 1GB is a better choice, but it probably won't make a huge difference. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 2400 (10%)

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 information (measured in megabytes per second) that can be transported over the external memory interface within a second. It is worked out by multiplying the interface width by the speed of its memory. In the case of DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The better 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 maximum number of pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines 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 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 get to the max fill rate.