Radeon HD 4850 2GB vs Radeon HD 7870

Intro

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

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 should be 142% quicker than the Radeon HD 4850 2GB in general, because of its greater bandwidth. (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%) better at anisotropic filtering 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

The Radeon HD 7870 is a lot (about 220%) better at FSAA than the Radeon HD 4850 2GB, and also able to handle higher screen resolutions more effectively. (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: Bandwidth is the largest amount of data (counted in MB per second) that can be moved past the external memory interface in a second. The number is worked out by multiplying the interface width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the 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 amount of texture map elements (texels) that can be applied per second. This number is worked out by multiplying the total texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.