GeForce 920M vs GeForce GT 640 DDR3

Intro

Compare all of that to the GeForce GT 640 DDR3, which comes with core speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 RAM. It features 384 SPUs as well as 32 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Benchmarks

These are real-world performance benchmarks that were submitted by Hardware Compare users. The scores seen here are the average of all benchmarks submitted for each respective test and hardware.

3DMark Fire Strike Graphics Score

GeForce GT 640 DDR3		1560 points
GeForce 920M		1180 points
	Difference: 380 (32%)

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically, the GeForce GT 640 DDR3 should perform much faster than the GeForce 920M in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 920M		14400 MB/sec
	Difference: 42624 (296%)

Texel Rate

The GeForce 920M will be just a bit (approximately 6%) faster with regards to anisotropic filtering than the GeForce GT 640 DDR3. (explain)

GeForce 920M		30528 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 1728 (6%)

Pixel Rate

The GeForce GT 640 DDR3 will be a lot (about 89%) faster with regards to full screen anti-aliasing than the GeForce 920M, and will be capable of handling higher resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 920M		7632 Mpixels/sec
	Difference: 6768 (89%)

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 largest amount of data (counted in megabytes per second) that can be transferred over the external memory interface within a second. It's calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.