Radeon HD 3870 X2 512MB vs Radeon HD 4750

Intro

Compare those specifications to the Radeon HD 4750, which makes use of a 40 nm design. AMD has set the core frequency at 730 MHz. The GDDR5 memory works at a speed of 800 MHz on this particular model. It features 640(128x5) SPUs along with 32 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3870 X2 512MB should in theory be a lot superior to the Radeon HD 4750 in general. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 4750		51200 MB/sec
	Difference: 64000 (125%)

Texel Rate

The Radeon HD 3870 X2 512MB will be a little bit (more or less 13%) more effective at AF than the Radeon HD 4750. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 4750		23360 Mtexels/sec
	Difference: 3040 (13%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 3870 X2 512MB is the winner, by far. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 4750		11680 Mpixels/sec
	Difference: 14720 (126%)

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 maximum amount of data (measured in MB per second) that can be transferred over the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory speed. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour 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 fill rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.