Radeon HD 4550 256MB vs Radeon HD 4650 512MB

Intro

Compare that to the Radeon HD 4650 512MB, which has a clock frequency of 600 MHz and a DDR2 memory frequency of 500 MHz. It also features a 128-bit bus, and uses a 55 nm design. It is made up of 320(64x5) SPUs, 32 Texture Address Units, and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4550 256MB		25 Watts
Radeon HD 4650 512MB		55 Watts
	Difference: 30 Watts (120%)

Memory Bandwidth

In theory, the Radeon HD 4650 512MB is 25% quicker than the Radeon HD 4550 256MB in general, because of its greater bandwidth. (explain)

Radeon HD 4650 512MB		16000 MB/sec
Radeon HD 4550 256MB		12800 MB/sec
	Difference: 3200 (25%)

Texel Rate

The Radeon HD 4650 512MB is much (about 300%) faster with regards to AF than the Radeon HD 4550 256MB. (explain)

Radeon HD 4650 512MB		19200 Mtexels/sec
Radeon HD 4550 256MB		4800 Mtexels/sec
	Difference: 14400 (300%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 4650 512MB is the winner, by far. (explain)

Radeon HD 4650 512MB		4800 Mpixels/sec
Radeon HD 4550 256MB		2400 Mpixels/sec
	Difference: 2400 (100%)

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 max amount of information (in units of megabytes per second) that can be moved across the external memory interface in a second. It's calculated by multiplying the interface width by its memory speed. In the case of DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, 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 in one second. This figure is worked out by multiplying the total texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.