Radeon HD 4850 2GB vs Radeon HD 7870

Intro

Compare those specifications to the Radeon HD 7870, which has a clock frequency of 1000 MHz and a GDDR5 memory speed of 1200 MHz. It also uses a 256-bit bus, and uses a 28 nm design. It is comprised of 1280 SPUs, 80 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 7870		175 Watts
	Difference: 65 Watts (59%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 should be much faster than the Radeon HD 4850 2GB overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 90048 (142%)

Texel Rate

The Radeon HD 7870 will be quite a bit (more or less 220%) faster with regards to AF than the Radeon HD 4850 2GB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 55000 (220%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7870 is a better choice, by a large margin. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4850 2GB		10000 Mpixels/sec
	Difference: 22000 (220%)

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 (measured in MB per second) that can be moved past the external memory interface within a second. The number is calculated by multiplying the bus width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the clock speed of the card. 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 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.