Radeon HD 4850 2GB vs Radeon HD 7850

Intro

Compare that to the Radeon HD 7850, which comes with a core clock frequency of 860 MHz and a GDDR5 memory speed of 1200 MHz. It also uses a 256-bit memory bus, and makes use of a 28 nm design. It is comprised of 1024 SPUs, 64 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 2GB		110 Watts
Radeon HD 7850		130 Watts
	Difference: 20 Watts (18%)

Memory Bandwidth

Theoretically, the Radeon HD 7850 should perform quite a bit faster than the Radeon HD 4850 2GB in general. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 90048 (142%)

Texel Rate

The Radeon HD 7850 will be quite a bit (approximately 120%) more effective at texture filtering than the Radeon HD 4850 2GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 30040 (120%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 7850 is superior to the Radeon HD 4850 2GB, by far. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4850 2GB		10000 Mpixels/sec
	Difference: 17520 (175%)

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 maximum amount of information (in units of megabytes per second) that can be transported across the external memory interface in one second. It's calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of 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.