Radeon HD 4890 2GB vs Radeon HD 7850

Intro

Compare those specs to the Radeon HD 7850, which comes with a GPU core clock speed of 860 MHz, and 2048 MB of GDDR5 memory set to run at 1200 MHz through a 256-bit bus. It also is comprised of 1024 SPUs, 64 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7850		130 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 60 Watts (46%)

Memory Bandwidth

The Radeon HD 7850, in theory, should perform a lot faster than the Radeon HD 4890 2GB overall. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 28800 (23%)

Texel Rate

The Radeon HD 7850 should be much (more or less 38%) better at texture filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 15040 (38%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7850 is the winner, and very much so. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 11520 (72%)

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 data (counted in MB per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This is worked out by multiplying the total texture units by the core speed of the chip. The better 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory in one 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 - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.