Radeon HD 3850 256MB vs Radeon HD 4850 512MB

Intro

Compare all of that to the Radeon HD 4850 512MB, which comes with a GPU core clock speed of 625 MHz, and 512 MB of GDDR3 RAM set to run at 993 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 35 Watts (47%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 512MB is 20% quicker than the Radeon HD 3850 256MB overall, due to its greater data rate. (explain)

Radeon HD 4850 512MB		63552 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 10560 (20%)

Texel Rate

The Radeon HD 4850 512MB is quite a bit (more or less 134%) faster with regards to texture filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 14312 (134%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 3850 256MB is the winner, not by a very large margin though. (explain)

Radeon HD 3850 256MB		10688 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 688 (7%)

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

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This figure is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at handling 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 that the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour ROPs by the the core clock speed. 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 many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.