GeForce 820M vs GeForce 840M

Intro

Compare those specifications to the GeForce 840M, which features core speeds of 1029 MHz on the GPU, and 1000 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs along with 24 TAUs and 8 Rasterization Operator 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 840M		1600 points
GeForce 820M		850 points
	Difference: 750 (88%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 840M		30 Watts
	Difference: 15 Watts (100%)

Memory Bandwidth

Both cards have exactly the same bandwidth, so theoretically they should have identical performance. (explain)

Texel Rate

The GeForce 840M is much (approximately 115%) more effective at AF than the GeForce 820M. (explain)

GeForce 840M		24696 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 13192 (115%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the GeForce 840M is a better choice, and very much so. (explain)

GeForce 840M		8232 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 5356 (186%)

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 (in units of MB per second) that can be transported over the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory speed. If it uses DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.