Radeon HD 3850 1GB vs Radeon HD 4850 512MB

Intro

Compare all that to the Radeon HD 4850 512MB, which comes with a core clock frequency of 625 MHz and a GDDR3 memory speed of 993 MHz. It also makes use of a 256-bit bus, and uses a 55 nm design. It is made up of 800(160x5) SPUs, 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 1GB		75 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 35 Watts (47%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 512MB will be 20% faster than the Radeon HD 3850 1GB in general, because of its greater bandwidth. (explain)

Radeon HD 4850 512MB		63552 MB/sec
Radeon HD 3850 1GB		52992 MB/sec
	Difference: 10560 (20%)

Texel Rate

The Radeon HD 4850 512MB will be a lot (about 134%) better at anisotropic filtering than the Radeon HD 3850 1GB. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 3850 1GB		10688 Mtexels/sec
	Difference: 14312 (134%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 3850 1GB is superior to the Radeon HD 4850 512MB, but it probably won't make a huge difference. (explain)

Radeon HD 3850 1GB		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: Bandwidth is the largest amount of data (measured in megabytes per second) that can be transferred past the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs 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 rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.