Radeon HD 3870 1GB vs Radeon HD 4850 2GB

Intro

Compare those specifications to the Radeon HD 4850 2GB, which comes with core clock speeds of 625 MHz on the GPU, and 993 MHz on the 2048 MB of GDDR4 memory. 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 1GB		106 Watts
Radeon HD 4850 2GB		110 Watts
	Difference: 4 Watts (4%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 1GB will be 13% quicker than the Radeon HD 4850 2GB in general, because of its greater data rate. (explain)

Radeon HD 3870 1GB		72000 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 8448 (13%)

Texel Rate

The Radeon HD 4850 2GB should be much (about 102%) better at anisotropic filtering than the Radeon HD 3870 1GB. (explain)

Radeon HD 4850 2GB		25000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 12600 (102%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 3870 1GB is superior to the Radeon HD 4850 2GB, by a large margin. (explain)

Radeon HD 3870 1GB		12400 Mpixels/sec
Radeon HD 4850 2GB		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 maximum amount of information (counted in MB per second) that can be moved past the external memory interface in one second. It's calculated by multiplying the card's bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This is worked out by multiplying the total 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 applied in one second.

Pixel Rate: Pixel rate is the most pixels 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 amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.