GeForce GT 640 DDR3 vs Radeon HD 3850 1GB

Intro

Compare those specifications to the Radeon HD 3850 1GB, which uses a 55 nm design. AMD has set the core speed at 668 MHz. The GDDR3 RAM runs at a frequency of 828 MHz on this specific model. It features 320(64x5) SPUs along with 16 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 3850 1GB		75 Watts
	Difference: 10 Watts (15%)

Memory Bandwidth

Performance-wise, the GeForce GT 640 DDR3 should in theory be just a bit superior to the Radeon HD 3850 1GB overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
Radeon HD 3850 1GB		52992 MB/sec
	Difference: 4032 (8%)

Texel Rate

The GeForce GT 640 DDR3 will be a lot (more or less 169%) faster with regards to texture filtering than the Radeon HD 3850 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 3850 1GB		10688 Mtexels/sec
	Difference: 18112 (169%)

Pixel Rate

If using high levels of AA is important to you, then the GeForce GT 640 DDR3 is a better choice, by a large margin. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 3850 1GB		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: Bandwidth is the max amount of information (measured in megabytes per second) that can be moved over the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, 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 applied in one second. This is calculated by multiplying the total texture units by the core speed of the chip. The better the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel 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 potential to get to the maximum fill rate.