Radeon HD 4850 2GB vs Radeon HD 7870

Intro

Compare those specs to the Radeon HD 7870, which features a core clock speed of 1000 MHz and a GDDR5 memory frequency of 1200 MHz. It also features a 256-bit memory bus, and uses a 28 nm design. It is made up 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

Performance-wise, the Radeon HD 7870 should theoretically be much better 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 much (approximately 220%) more effective 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

If running with high levels of AA is important to you, then the Radeon HD 7870 is a better choice, and very much so. (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 largest amount of data (measured in MB per second) that can be transported past the external memory interface in one second. It is calculated by multiplying the bus width by its memory clock speed. If the card has DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen 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 number of texture units of the card by the core clock speed of the chip. The higher this number, 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 most pixels that the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.