Radeon HD 3870 1GB vs Radeon HD 4850 1GB

Intro

Compare those specs to the Radeon HD 4850 1GB, which makes use of a 55 nm design. AMD has set the core speed at 625 MHz. The GDDR4 RAM works at a frequency of 993 MHz on this particular model. It features 800(160x5) SPUs along with 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 1GB		106 Watts
Radeon HD 4850 1GB		110 Watts
	Difference: 4 Watts (4%)

Memory Bandwidth

Performance-wise, the Radeon HD 3870 1GB should in theory be just a bit better than the Radeon HD 4850 1GB in general. (explain)

Radeon HD 3870 1GB		72000 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 8448 (13%)

Texel Rate

The Radeon HD 4850 1GB is much (about 102%) more effective at texture filtering than the Radeon HD 3870 1GB. (explain)

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

Pixel Rate

The Radeon HD 3870 1GB is a lot (more or less 24%) more effective at anti-aliasing than the Radeon HD 4850 1GB, and also capable of handling higher screen resolutions better. (explain)

Radeon HD 3870 1GB		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 information (measured in MB per second) that can be moved over the external memory interface in one second. It's worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.