Radeon HD 3870 1GB vs Radeon HD 4830 512MB

Intro

Compare all that to the Radeon HD 4830 512MB, which comes with core clock speeds of 575 MHz on the GPU, and 900 MHz on the 512 MB of GDDR3 RAM. It features 640(128x5) SPUs along with 32 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4830 512MB		95 Watts
Radeon HD 3870 1GB		106 Watts
	Difference: 11 Watts (12%)

Memory Bandwidth

In theory, the Radeon HD 3870 1GB will be 25% faster than the Radeon HD 4830 512MB overall, due to its higher data rate. (explain)

Radeon HD 3870 1GB		72000 MB/sec
Radeon HD 4830 512MB		57600 MB/sec
	Difference: 14400 (25%)

Texel Rate

The Radeon HD 4830 512MB will be a lot (about 48%) faster with regards to AF than the Radeon HD 3870 1GB. (explain)

Radeon HD 4830 512MB		18400 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 6000 (48%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 3870 1GB is a better choice, and very much so. (explain)

Radeon HD 3870 1GB		12400 Mpixels/sec
Radeon HD 4830 512MB		9200 Mpixels/sec
	Difference: 3200 (35%)

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 information (counted in MB per second) that can be transferred over the external memory interface in one second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. 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 is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.