Radeon HD 4650 512MB vs Radeon HD 6850

Intro

Compare those specifications to the Radeon HD 6850, which has clock speeds of 775 MHz on the GPU, and 1000 MHz on the 1024 MB of GDDR5 memory. It features 960 SPUs along with 48 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 6850		127 Watts
	Difference: 72 Watts (131%)

Memory Bandwidth

The Radeon HD 6850 should in theory be quite a bit faster than the Radeon HD 4650 512MB overall. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 112000 (700%)

Texel Rate

The Radeon HD 6850 is much (more or less 94%) better at anisotropic filtering than the Radeon HD 4650 512MB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 18000 (94%)

Pixel Rate

The Radeon HD 6850 should be a lot (more or less 417%) faster with regards to FSAA than the Radeon HD 4650 512MB, and will be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 20000 (417%)

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 largest amount of information (in units of MB per second) that can be transported across the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. If it uses DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster 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 can be processed per second. This is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill 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.