Radeon HD 4870 X2 vs Radeon HD 4890 1GB

Intro

Compare those specifications to the Radeon HD 4890 1GB, which features core speeds of 1000 MHz on the GPU, and 975 MHz on the 1024 MB of GDDR5 RAM. It features 800(160x5) SPUs as well as 40 TAUs and 16 Rasterization Operator 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

Performance-wise, the Radeon HD 4870 X2 should theoretically be a lot better 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 is much (about 50%) more effective at texture 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

The Radeon HD 4870 X2 will be a lot (more or less 50%) faster with regards to anti-aliasing than the Radeon HD 4890 1GB, and should be able to handle higher resolutions better. (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 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 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, 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 number of texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

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