Radeon HD 4850 X2 1GB vs Radeon HD 4870 2GB

Intro

Compare those specs to the Radeon HD 4870 2GB, which comes with GPU core speed of 750 MHz, and 2048 MB of GDDR5 memory set to run at 900 MHz through a 256-bit bus. It also is comprised of 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 4870 2GB		150 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 100 Watts (67%)

Memory Bandwidth

Performance-wise, the Radeon HD 4850 X2 1GB should in theory be a bit superior to the Radeon HD 4870 2GB in general. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 11904 (10%)

Texel Rate

The Radeon HD 4850 X2 1GB is much (approximately 67%) more effective at AF than the Radeon HD 4870 2GB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 20000 (67%)

Pixel Rate

The Radeon HD 4850 X2 1GB is much (approximately 67%) better at FSAA than the Radeon HD 4870 2GB, and capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 4870 2GB		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: Bandwidth is the maximum amount of data (in units of MB per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This number is calculated by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that 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 Raster Operations Pipelines 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 rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.