Radeon HD 3870 X2 1GB vs Radeon HD 7850

Intro

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

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 7850 should in theory perform a bit faster than the Radeon HD 3870 X2 1GB in general. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 9472 (7%)

Texel Rate

The Radeon HD 7850 should be a lot (approximately 108%) more effective at texture filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 28640 (108%)

Pixel Rate

The Radeon HD 7850 will be a small bit (about 4%) more effective at FSAA than the Radeon HD 3870 X2 1GB, and able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 3870 X2 1GB		26400 Mpixels/sec
	Difference: 1120 (4%)

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: Bandwidth is the largest amount of information (in units of MB per second) that can be transported over the external memory interface in a second. It's calculated by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed 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 the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could 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 ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.