Radeon HD 3850 256MB vs Radeon HD 4850 1GB

Intro

Compare those specifications to the Radeon HD 4850 1GB, which features a GPU core clock speed of 625 MHz, and 1024 MB of GDDR4 RAM running at 993 MHz through a 256-bit bus. It also features 800(160x5) SPUs, 40 TAUs, 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 1GB		110 Watts
	Difference: 35 Watts (47%)

Memory Bandwidth

In theory, the Radeon HD 4850 1GB will be 20% quicker than the Radeon HD 3850 256MB in general, due to its higher bandwidth. (explain)

Radeon HD 4850 1GB		63552 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 10560 (20%)

Texel Rate

The Radeon HD 4850 1GB should be much (approximately 134%) faster with regards to anisotropic filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 4850 1GB		25000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 14312 (134%)

Pixel Rate

The Radeon HD 3850 256MB should be a little bit (more or less 7%) more effective at full screen anti-aliasing than the Radeon HD 4850 1GB, and also capable of handling higher resolutions without slowing down too much. (explain)

Radeon HD 3850 256MB		10688 Mpixels/sec
Radeon HD 4850 1GB		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 information (measured in MB per second) that can be transferred past the external memory interface in a second. It is calculated by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, 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 number of texture map elements (texels) that are processed in one second. This figure is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to its local memory per 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 - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.