GeForce GTX 650 vs Radeon HD 3870 X2 1GB

Intro

Compare that to the Radeon HD 3870 X2 1GB, which comes with clock speeds of 825 MHz on the GPU, and 1126 MHz on the 1024 MB of GDDR4 memory. It features 320(64x5) SPUs along with 16 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 1GB will be 80% quicker than the GeForce GTX 650 overall, because of its greater data rate. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
GeForce GTX 650		80000 MB/sec
	Difference: 64128 (80%)

Texel Rate

The GeForce GTX 650 is a lot (more or less 28%) more effective at AF than the Radeon HD 3870 X2 1GB. (explain)

GeForce GTX 650		33856 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 7456 (28%)

Pixel Rate

The Radeon HD 3870 X2 1GB should be a lot (more or less 56%) more effective at FSAA than the GeForce GTX 650, and also will be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 1GB		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: Memory bandwidth is the largest amount of data (counted in megabytes per second) that can be moved across the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory speed. If the card has DDR type memory, the result should be multiplied by 2 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 AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the graphics card will be at handling 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 chip could possibly record to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.