Radeon HD 4850 512MB vs Radeon HD 4890 1GB

Intro

Compare those specs to the Radeon HD 4890 1GB, which makes use of a 55 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 memory works at a frequency of 975 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 512MB		110 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 80 Watts (73%)

Memory Bandwidth

Performance-wise, the Radeon HD 4890 1GB should theoretically be quite a bit superior to the Radeon HD 4850 512MB in general. (explain)

Radeon HD 4890 1GB		124800 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 61248 (96%)

Texel Rate

The Radeon HD 4890 1GB will be quite a bit (about 60%) faster with regards to anisotropic filtering than the Radeon HD 4850 512MB. (explain)

Radeon HD 4890 1GB		40000 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 15000 (60%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 4890 1GB is the winner, by far. (explain)

Radeon HD 4890 1GB		16000 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 6000 (60%)

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 past the external memory interface within a second. It is calculated by multiplying the interface width by its memory speed. If the card has DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total number of texture units 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 can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.