Radeon HD 4870 X2 vs Radeon HD 4890 2GB

Intro

Compare those specs to the Radeon HD 4890 2GB, which uses a 55 nm design. AMD has set the core speed at 1000 MHz. The GDDR5 RAM is set to run at a frequency of 975 MHz on this particular card. It features 800(160x5) SPUs as well as 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 2GB		190 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 160 Watts (84%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 X2 should in theory be much superior to the Radeon HD 4890 2GB in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 105600 (85%)

Texel Rate

The Radeon HD 4870 X2 will be much (more or less 50%) faster with regards to anisotropic filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 20000 (50%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 4870 X2 is superior to the Radeon HD 4890 2GB, by far. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 8000 (50%)

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 maximum amount of data (counted in megabytes per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total number of texture units by the core 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 in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.