Radeon HD 3870 512MB vs Radeon HD 4850 1GB

Intro

Compare those specifications to the Radeon HD 4850 1GB, which uses a 55 nm design. AMD has clocked the core speed at 625 MHz. The GDDR4 memory works at a speed of 993 MHz on this model. It features 800(160x5) SPUs as well as 40 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 3870 512MB		106 Watts
Radeon HD 4850 1GB		110 Watts
	Difference: 4 Watts (4%)

Memory Bandwidth

In theory, the Radeon HD 4850 1GB is 10% faster than the Radeon HD 3870 512MB overall, because of its greater bandwidth. (explain)

Radeon HD 4850 1GB		63552 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 5952 (10%)

Texel Rate

The Radeon HD 4850 1GB should be quite a bit (approximately 102%) better at texture filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4850 1GB		25000 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 12600 (102%)

Pixel Rate

The Radeon HD 3870 512MB should be much (approximately 24%) more effective at FSAA than the Radeon HD 4850 1GB, and also should be capable of handling higher resolutions while still performing well. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 4850 1GB		10000 Mpixels/sec
	Difference: 2400 (24%)

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 largest amount of data (counted in MB per second) that can be transferred past the external memory interface in a second. It is worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed in one second. This figure is calculated by multiplying the total amount of texture units of the card by the core 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 processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines 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 output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.