Radeon HD 3870 512MB vs Radeon HD 4850 X2 1GB

Intro

Compare those specs to the Radeon HD 4850 X2 1GB, which comes with a clock frequency of 625 MHz and a GDDR3 memory speed of 993 MHz. It also makes use of a 256-bit memory bus, and uses a 55 nm design. It is comprised 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 3870 512MB		106 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 144 Watts (136%)

Memory Bandwidth

The Radeon HD 4850 X2 1GB, in theory, should be a lot faster than the Radeon HD 3870 512MB overall. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 69504 (121%)

Texel Rate

The Radeon HD 4850 X2 1GB will be a lot (approximately 303%) faster with regards to anisotropic filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 37600 (303%)

Pixel Rate

The Radeon HD 4850 X2 1GB should be much (about 61%) more effective at AA than the Radeon HD 3870 512MB, and also capable of handling higher screen resolutions better. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 3870 512MB		12400 Mpixels/sec
	Difference: 7600 (61%)

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 (counted in MB per second) that can be transported across the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.