GeForce GT 640 DDR3 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 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3870 X2 1GB should in theory be much superior to the GeForce GT 640 DDR3 in general. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 87104 (153%)

Texel Rate

The GeForce GT 640 DDR3 is a small bit (more or less 9%) better at anisotropic filtering than the Radeon HD 3870 X2 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 2400 (9%)

Pixel Rate

The Radeon HD 3870 X2 1GB is a lot (approximately 83%) more effective at FSAA than the GeForce GT 640 DDR3, and also will be able to handle higher screen resolutions better. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 12000 (83%)

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 maximum amount of information (in units of MB per second) that can be moved past the external memory interface within a second. It is calculated by multiplying the interface width by its memory speed. If it uses DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster 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 amount of texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total number of texture units by the core speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. 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 maximum fill rate.