GeForce 820M vs GeForce GT 640 DDR3

Intro

Compare all of that to the GeForce GT 640 DDR3, which has a core clock speed of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also makes use of a 128-bit memory bus, and uses a 28 nm design. It is comprised of 384 SPUs, 32 TAUs, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

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 820M		850 points
	Difference: 710 (84%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 50 Watts (333%)

Memory Bandwidth

The GeForce GT 640 DDR3 should theoretically be much faster than the GeForce 820M overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 41024 (256%)

Texel Rate

The GeForce GT 640 DDR3 is a lot (approximately 150%) better at texture filtering than the GeForce 820M. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 17296 (150%)

Pixel Rate

The GeForce GT 640 DDR3 is a lot (more or less 401%) better at FSAA than the GeForce 820M, and also able to handle higher resolutions more effectively. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 11524 (401%)

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 data (counted in megabytes per second) that can be transported across the external memory interface within a second. It's calculated by multiplying the bus width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, 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 the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.