GeForce GT 640 DDR3 vs Radeon HD 3690/3830

Intro

Compare those specs to the Radeon HD 3690/3830, which features core clock speeds of 668 MHz on the GPU, and 828 MHz on the 256 MB of GDDR3 RAM. It features 320(64x5) SPUs along with 16 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 3690/3830		75 Watts
	Difference: 10 Watts (15%)

Memory Bandwidth

Theoretically, the GeForce GT 640 DDR3 should perform a lot faster than the Radeon HD 3690/3830 overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
Radeon HD 3690/3830		26496 MB/sec
	Difference: 30528 (115%)

Texel Rate

The GeForce GT 640 DDR3 should be quite a bit (about 169%) faster with regards to AF than the Radeon HD 3690/3830. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 3690/3830		10688 Mtexels/sec
	Difference: 18112 (169%)

Pixel Rate

If using a high resolution is important to you, then the GeForce GT 640 DDR3 is superior to the Radeon HD 3690/3830, by far. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 3690/3830		10688 Mpixels/sec
	Difference: 3712 (35%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of information (counted in megabytes per second) that can be moved over the external memory interface in a second. It's calculated by multiplying the bus width by the speed of its memory. If the card has DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better 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 per second. This number is worked out by multiplying the total number of texture units by the core speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card could 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 the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.