Radeon HD 3870 1GB vs Radeon HD 3870 512MB

Intro

Compare those specs to the Radeon HD 3870 512MB, which features a GPU core clock speed of 775 MHz, and 512 MB of GDDR3 memory set to run at 900 MHz through a 256-bit bus. It also is made up of 320(64x5) Stream Processors, 16 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Both cards have the same power consumption.

Memory Bandwidth

The Radeon HD 3870 1GB, in theory, should be much faster than the Radeon HD 3870 512MB in general. (explain)

Radeon HD 3870 1GB		72000 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 14400 (25%)

Texel Rate

Both cards have exactly the same texel fill rate, so theoretically they should perform equally good at at anisotropic filtering. (explain)

Pixel Rate

Both cards have the exact same pixel rate, so in theory they should perform equally good at at FSAA, and be able to handle the same screen resolutions. (explain)

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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (measured in megabytes per second) that can be transported over the external memory interface in a second. It's calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes 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, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.