GeForce GTX 650 vs Radeon HD 3870 X2 512MB

Intro

Compare all that to the Radeon HD 3870 X2 512MB, which has a core clock frequency of 825 MHz and a GDDR3 memory frequency of 900 MHz. It also makes use of a 256-bit memory bus, and uses a 55 nm design. It is comprised of 320(64x5) SPUs, 16 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 512MB should perform much faster than the GeForce GTX 650 overall. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
GeForce GTX 650		80000 MB/sec
	Difference: 35200 (44%)

Texel Rate

The GeForce GTX 650 should be much (about 28%) better at AF than the Radeon HD 3870 X2 512MB. (explain)

GeForce GTX 650		33856 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 7456 (28%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 3870 X2 512MB is superior to the GeForce GTX 650, by a large margin. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
GeForce GTX 650		16928 Mpixels/sec
	Difference: 9472 (56%)

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 megabytes per second) that can be transferred past 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 the card has DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total amount of texture units of the card by the core 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 processed per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the core 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 rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.