GeForce GT 420 vs GeForce GTX 850M

Intro

Compare those specifications to the GeForce GTX 850M, which comes with clock speeds of 876 MHz on the GPU, and 1000 MHz on the 2048 MB of DDR3 memory. It features 640 SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 850M		40 Watts
GeForce GT 420		50 Watts
	Difference: 10 Watts (25%)

Memory Bandwidth

In theory, the GeForce GTX 850M should be a bit faster than the GeForce GT 420 in general. (explain)

GeForce GTX 850M		32000 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 3200 (11%)

Texel Rate

The GeForce GTX 850M is quite a bit (about 526%) faster with regards to AF than the GeForce GT 420. (explain)

GeForce GTX 850M		35040 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 29440 (526%)

Pixel Rate

If using a high screen resolution is important to you, then the GeForce GTX 850M is the winner, and very much so. (explain)

GeForce GTX 850M		14016 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 11216 (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: Bandwidth is the largest amount of information (counted in MB per second) that can be transported over the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, 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 can be processed per second. This number is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. The number is worked out 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 drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.