Radeon HD 3870 X2 512MB vs Radeon HD 4770

Intro

Compare those specifications to the Radeon HD 4770, which features a clock speed of 750 MHz and a GDDR5 memory speed of 800 MHz. It also uses a 128-bit memory bus, and makes use of a 40 nm design. It is comprised of 640(128x5) SPUs, 32 TAUs, and 16 Raster Operation 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 4770 in general. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 64000 (125%)

Texel Rate

The Radeon HD 3870 X2 512MB is a bit (about 10%) faster with regards to texture filtering than the Radeon HD 4770. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 2400 (10%)

Pixel Rate

The Radeon HD 3870 X2 512MB will be quite a bit (more or less 120%) better at full screen anti-aliasing than the Radeon HD 4770, and also should be capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 4770		12000 Mpixels/sec
	Difference: 14400 (120%)

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 transferred across the external memory interface within a second. It's worked out by multiplying the card's interface width by the speed of its memory. If it uses DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, 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 texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.