Radeon HD 3850 512MB vs Radeon HD 4650 512MB

Intro

Compare all that to the Radeon HD 4650 512MB, which has core clock speeds of 600 MHz on the GPU, and 500 MHz on the 512 MB of DDR2 memory. It features 320(64x5) SPUs as well as 32 Texture Address Units and 8 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 3850 512MB		75 Watts
	Difference: 20 Watts (36%)

Memory Bandwidth

The Radeon HD 3850 512MB should in theory perform a lot faster than the Radeon HD 4650 512MB overall. (explain)

Radeon HD 3850 512MB		52992 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 36992 (231%)

Texel Rate

The Radeon HD 4650 512MB should be quite a bit (approximately 80%) more effective at texture filtering than the Radeon HD 3850 512MB. (explain)

Radeon HD 4650 512MB		19200 Mtexels/sec
Radeon HD 3850 512MB		10688 Mtexels/sec
	Difference: 8512 (80%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 3850 512MB is the winner, and very much so. (explain)

Radeon HD 3850 512MB		10688 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 5888 (123%)

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 max amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. It's worked out by multiplying the interface width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's 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 can be processed per second. This number is calculated by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate 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 filling the screen with pixels (the image). The actual pixel rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.