GeForce GT 340 vs GeForce GT 640 DDR3

Intro

Compare that to the GeForce GT 640 DDR3, which has core speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 RAM. It features 384 SPUs along with 32 Texture Address Units and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GT 340		69 Watts
	Difference: 4 Watts (6%)

Memory Bandwidth

Theoretically speaking, the GeForce GT 640 DDR3 should be 5% faster than the GeForce GT 340 overall, because of its greater data rate. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce GT 340		54400 MB/sec
	Difference: 2624 (5%)

Texel Rate

The GeForce GT 640 DDR3 will be much (about 64%) more effective at anisotropic filtering than the GeForce GT 340. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GT 340		17600 Mtexels/sec
	Difference: 11200 (64%)

Pixel Rate

The GeForce GT 640 DDR3 will be much (about 227%) faster with regards to AA than the GeForce GT 340, and also capable of handling higher screen resolutions more effectively. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GT 340		4400 Mpixels/sec
	Difference: 10000 (227%)

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 (in units of megabytes per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the bus width by the speed of its memory. If the card has DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's 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 number of texture map elements (texels) that can be applied in one second. This number is calculated by multiplying the total number of texture units by the core speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.