Radeon HD 3870 1GB vs Radeon HD 4830 1GB

Intro

Compare that to the Radeon HD 4830 1GB, which has a clock frequency of 575 MHz and a GDDR4 memory speed of 900 MHz. It also uses a 256-bit memory bus, and uses a 55 nm design. It is made up of 640(128x5) SPUs, 32 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

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

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 1GB will be 25% faster than the Radeon HD 4830 1GB overall, due to its greater data rate. (explain)

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

Texel Rate

The Radeon HD 4830 1GB is quite a bit (approximately 48%) better at anisotropic filtering than the Radeon HD 3870 1GB. (explain)

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

Pixel Rate

The Radeon HD 3870 1GB is a lot (about 35%) better at anti-aliasing than the Radeon HD 4830 1GB, and able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 3870 1GB		12400 Mpixels/sec
Radeon HD 4830 1GB		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 max amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. It's calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR memory, the result should 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, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure 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 video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.