GeForce GT 640 DDR3 vs Radeon HD 3850 X2

Intro

Compare that to the Radeon HD 3850 X2, which makes use of a 55 nm design. AMD has clocked the core speed at 668 MHz. The GDDR3 RAM runs at a frequency of 828 MHz on this card. It features 320(64x5) SPUs as well as 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 3850 X2 should in theory be quite a bit better than the GeForce GT 640 DDR3 overall. (explain)

Radeon HD 3850 X2		105984 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 48960 (86%)

Texel Rate

The GeForce GT 640 DDR3 will be quite a bit (about 35%) better at anisotropic filtering than the Radeon HD 3850 X2. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 7424 (35%)

Pixel Rate

The Radeon HD 3850 X2 is quite a bit (approximately 48%) better at AA than the GeForce GT 640 DDR3, and also will be capable of handling higher resolutions without slowing down too much. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 6976 (48%)

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 maximum amount of information (counted in megabytes per second) that can be moved over the external memory interface within a second. The number is calculated by multiplying the bus width by its memory speed. If it uses DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This number is calculated by multiplying the total texture units by the core speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.