Radeon HD 3870 X2 1GB vs Radeon HD 4650 512MB

Intro

Compare those specifications to the Radeon HD 4650 512MB, which makes use of a 55 nm design. AMD has clocked the core speed at 600 MHz. The DDR2 RAM works at a frequency of 500 MHz on this specific card. It features 320(64x5) SPUs along with 32 TAUs and 8 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3870 X2 1GB should in theory be quite a bit superior to the Radeon HD 4650 512MB overall. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 128128 (801%)

Texel Rate

The Radeon HD 3870 X2 1GB is a lot (approximately 38%) better at anisotropic filtering than the Radeon HD 4650 512MB. (explain)

Radeon HD 3870 X2 1GB		26400 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 7200 (38%)

Pixel Rate

The Radeon HD 3870 X2 1GB should be a lot (approximately 450%) better at AA than the Radeon HD 4650 512MB, and also will be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 21600 (450%)

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 (measured in MB per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the interface width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better 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 are applied in one second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher 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 that the graphics chip could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.