Radeon HD 3870 1GB vs Radeon HD 4830 512MB

Intro

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

(No game benchmarks for this combination yet.)

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 should perform quite a bit faster than the Radeon HD 4830 512MB overall. (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 should be much (more or less 48%) better at texture filtering 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

The Radeon HD 3870 1GB is much (approximately 35%) faster with regards to FSAA than the Radeon HD 4830 512MB, and will be able to handle higher resolutions without losing too much performance. (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 max amount of information (measured in MB per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied 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 higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as 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 of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.