Radeon HD 4870 X2 vs Radeon HD 7850

Intro

Compare all of that to the Radeon HD 7850, which uses a 28 nm design. AMD has clocked the core frequency at 860 MHz. The GDDR5 memory runs at a speed of 1200 MHz on this card. It features 1024 SPUs as well as 64 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7850		130 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 220 Watts (169%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should be much faster than the Radeon HD 7850 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 7850		153600 MB/sec
	Difference: 76800 (50%)

Texel Rate

The Radeon HD 4870 X2 is a bit (about 9%) better at AF than the Radeon HD 7850. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 7850		55040 Mtexels/sec
	Difference: 4960 (9%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7850 is a better choice, but only just. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 3520 (15%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of data (measured in megabytes per second) that can be moved over the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory speed. If the card has DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total number of texture units of the card 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the core 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 rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.