GeForce GT 420 vs GeForce GTX 850M

Intro

Compare those specifications to the GeForce GTX 850M, which has a core clock speed of 876 MHz and a DDR3 memory frequency of 1000 MHz. It also uses a 128-bit memory bus, and makes use of a 28 nm design. It is made up of 640 SPUs, 40 Texture Address Units, and 16 ROPs.

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

Performance-wise, the GeForce GTX 850M should in theory be just a bit superior to 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 should be quite a bit (more or less 526%) more effective at AF than the GeForce GT 420. (explain)

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

Pixel Rate

The GeForce GTX 850M is much (approximately 401%) faster with regards to FSAA than the GeForce GT 420, and also able to handle higher resolutions while still performing well. (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 maximum amount of data (measured in megabytes per second) that can be moved over the external memory interface in a second. It is worked out by multiplying the bus width by its memory speed. In the case of DDR RAM, the result should be multiplied by 2 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 AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units 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 rate is also dependant on lots of 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.