Radeon HD 4870 X2 vs Radeon HD 4890 1GB

Intro

Compare those specs to the Radeon HD 4890 1GB, which features GPU clock speed of 1000 MHz, and 1024 MB of GDDR5 RAM set to run at 975 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 1GB		190 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 160 Watts (84%)

Memory Bandwidth

The Radeon HD 4870 X2 should in theory perform a lot faster than the Radeon HD 4890 1GB in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 105600 (85%)

Texel Rate

The Radeon HD 4870 X2 will be much (approximately 50%) more effective at anisotropic filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 20000 (50%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 4870 X2 is superior to the Radeon HD 4890 1GB, by a large margin. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 4890 1GB		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 max amount of information (measured in megabytes per second) that can be transported across the external memory interface in a second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the 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 number of texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.