Radeon HD 4850 X2 1GB vs Radeon HD 4870 1GB

Intro

Compare those specs to the Radeon HD 4870 1GB, which comes with GPU clock speed of 750 MHz, and 1024 MB of GDDR5 RAM running at 900 MHz through a 256-bit bus. It also 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 1GB		150 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 100 Watts (67%)

Memory Bandwidth

The Radeon HD 4850 X2 1GB, in theory, should be just a bit faster than the Radeon HD 4870 1GB overall. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 4870 1GB		115200 MB/sec
	Difference: 11904 (10%)

Texel Rate

The Radeon HD 4850 X2 1GB is much (more or less 67%) better at AF than the Radeon HD 4870 1GB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 20000 (67%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 4850 X2 1GB is superior to the Radeon HD 4870 1GB, by far. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 4870 1GB		12000 Mpixels/sec
	Difference: 8000 (67%)

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 maximum amount of information (counted in megabytes per second) that can be transported past the external memory interface within a second. The number is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the 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 number of texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total number of 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 one second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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 - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.