Radeon HD 3850 X2 vs Radeon HD 4870 512MB

Intro

Compare those specs to the Radeon HD 4870 512MB, which has clock speeds of 750 MHz on the GPU, and 900 MHz on the 512 MB of GDDR5 RAM. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 4870 512MB should theoretically be a bit superior to the Radeon HD 3850 X2 overall. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 3850 X2		105984 MB/sec
	Difference: 9216 (9%)

Texel Rate

The Radeon HD 4870 512MB is quite a bit (more or less 40%) more effective at texture filtering than the Radeon HD 3850 X2. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 8624 (40%)

Pixel Rate

The Radeon HD 3850 X2 should be much (approximately 78%) better at AA than the Radeon HD 4870 512MB, and able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 9376 (78%)

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 data (measured in MB per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the bus width by the speed of its memory. If it uses DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel 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 maximum fill rate.