Radeon HD 3850 1GB vs Radeon HD 3870 512MB

Intro

Compare all that to the Radeon HD 3870 512MB, which features a core clock frequency of 775 MHz and a GDDR3 memory frequency of 900 MHz. It also uses a 256-bit bus, and makes use of a 55 nm design. It is made up of 320(64x5) SPUs, 16 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 1GB		75 Watts
Radeon HD 3870 512MB		106 Watts
	Difference: 31 Watts (41%)

Memory Bandwidth

Theoretically, the Radeon HD 3870 512MB should be just a bit faster than the Radeon HD 3850 1GB overall. (explain)

Radeon HD 3870 512MB		57600 MB/sec
Radeon HD 3850 1GB		52992 MB/sec
	Difference: 4608 (9%)

Texel Rate

The Radeon HD 3870 512MB should be a bit (more or less 16%) more effective at anisotropic filtering than the Radeon HD 3850 1GB. (explain)

Radeon HD 3870 512MB		12400 Mtexels/sec
Radeon HD 3850 1GB		10688 Mtexels/sec
	Difference: 1712 (16%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 3870 512MB is the winner, not by a very large margin though. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 3850 1GB		10688 Mpixels/sec
	Difference: 1712 (16%)

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: Memory bandwidth is the maximum amount of data (in units of megabytes per second) that can be transported over the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If 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 amount of texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total texture units of the card 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 applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.