GeForce 8800 GTX vs Radeon HD 3870 X2 1GB

Intro

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

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 1GB is 67% quicker than the GeForce 8800 GTX overall, due to its greater data rate. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
GeForce 8800 GTX		86400 MB/sec
	Difference: 57728 (67%)

Texel Rate

The GeForce 8800 GTX should be quite a bit (more or less 39%) faster with regards to texture filtering than the Radeon HD 3870 X2 1GB. (explain)

GeForce 8800 GTX		36800 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 10400 (39%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 3870 X2 1GB is a better choice, and very much so. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
GeForce 8800 GTX		13800 Mpixels/sec
	Difference: 12600 (91%)

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 moved across the external memory interface in a second. The number is worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better 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 are processed per second. This is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the clock 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 output rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.