Radeon HD 4850 2GB vs Radeon HD 7950 3GB

Intro

Compare that to the Radeon HD 7950 3GB, which has a GPU core clock speed of 800 MHz, and 3072 MB of GDDR5 RAM running at 1250 MHz through a 384-bit bus. It also is made up of 1792 SPUs, 112 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 2GB		110 Watts
Radeon HD 7950 3GB		200 Watts
	Difference: 90 Watts (82%)

Memory Bandwidth

The Radeon HD 7950 3GB, in theory, should perform much faster than the Radeon HD 4850 2GB in general. (explain)

Radeon HD 7950 3GB		240000 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 176448 (278%)

Texel Rate

The Radeon HD 7950 3GB is much (approximately 258%) more effective at AF than the Radeon HD 4850 2GB. (explain)

Radeon HD 7950 3GB		89600 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 64600 (258%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 7950 3GB is superior to the Radeon HD 4850 2GB, and very much so. (explain)

Radeon HD 7950 3GB		25600 Mpixels/sec
Radeon HD 4850 2GB		10000 Mpixels/sec
	Difference: 15600 (156%)

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 data (measured in MB per second) that can be moved past the external memory interface in a second. It is calculated by multiplying the interface width by its memory clock speed. If it uses 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 AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This number is worked out by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units 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 output rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.