Radeon HD 4870 2GB vs Radeon HD 4870 X2

Intro

Compare all that to the Radeon HD 4870 X2, which features a clock frequency of 750 MHz and a GDDR5 memory speed of 900 MHz. It also uses a 256-bit bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 2GB		150 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 200 Watts (133%)

Memory Bandwidth

The Radeon HD 4870 X2, in theory, should be a lot faster than the Radeon HD 4870 2GB overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 115200 (100%)

Texel Rate

The Radeon HD 4870 X2 should be a lot (about 100%) better at AF than the Radeon HD 4870 2GB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 30000 (100%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 4870 X2 is a better choice, and very much so. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 12000 (100%)

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 (in units of MB per second) that can be transferred over the external memory interface in one second. It is worked out by multiplying the card's interface width by its memory speed. If the card has DDR RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster 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 texture map elements (texels) that are processed in one second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the video 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 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 number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output 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 reach the maximum fill rate.