GeForce GTX 275 vs Radeon HD 3870 X2 1GB

Intro

Compare those specs to the Radeon HD 3870 X2 1GB, which makes use of a 55 nm design. ATi has clocked the core speed at 825 MHz. The GDDR4 RAM is set to run at a frequency of 1126 MHz on this specific model. It features 320(64x5) SPUs as well as 16 Texture Address Units and 16 Rasterization Operator Units.

(No game benchmarks for this combination yet.)

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, due to 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 will be quite a bit (approximately 92%) more effective at anisotropic 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

If using high levels of AA is important to you, then the Radeon HD 3870 X2 1GB is superior to the GeForce GTX 275, and very much so. (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: Memory bandwidth is the max amount of data (measured in megabytes per second) that can be transported past the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If it uses 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 amount of texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total texture units by the core speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output 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.