Radeon HD 3870 512MB vs Radeon HD 4850 1GB

Intro

Compare all that to the Radeon HD 4850 1GB, which has a clock speed of 625 MHz and a GDDR4 memory speed of 993 MHz. It also uses a 256-bit memory bus, and uses a 55 nm design. It is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

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

The Radeon HD 4850 1GB should in theory be just a bit faster than the Radeon HD 3870 512MB in general. (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 a lot (more or less 102%) better at anisotropic 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

If running with lots of anti-aliasing is important to you, then the Radeon HD 3870 512MB is a better choice, by far. (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: Bandwidth is the largest amount of information (counted in MB per second) that can be transported across the external memory interface within a second. The number is calculated by multiplying the bus width by its memory clock speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number 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 outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.