GeForce GTX 275 vs Radeon HD 3870 X2 1GB

Intro

Compare all of that to the Radeon HD 3870 X2 1GB, which features a GPU core clock speed of 825 MHz, and 1024 MB of GDDR4 RAM running at 1126 MHz through a 256-bit bus. It also is comprised of 320(64x5) SPUs, 16 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 X2 1GB will be 13% faster than the GeForce GTX 275 overall, because of its higher bandwidth. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
GeForce GTX 275		127008 MB/sec
	Difference: 17120 (13%)

Texel Rate

The GeForce GTX 275 is a lot (more or less 92%) better at texture filtering than the Radeon HD 3870 X2 1GB. (explain)

GeForce GTX 275		50640 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 24240 (92%)

Pixel Rate

The Radeon HD 3870 X2 1GB will be quite a bit (approximately 49%) better at anti-aliasing than the GeForce GTX 275, and also capable of handling higher screen resolutions more effectively. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
GeForce GTX 275		17724 Mpixels/sec
	Difference: 8676 (49%)

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 data (measured in megabytes per second) that can be transported across the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory speed. In the case of DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better 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 can be applied in one second. This is calculated by multiplying the total amount of texture units by the core speed of the chip. The higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many 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.