GeForce 820M vs GeForce GT 315

Intro

Compare those specifications to the GeForce GT 315, which uses a 40 nm design. nVidia has clocked the core frequency at 625 MHz. The DDR3 memory is set to run at a speed of 790 MHz on this specific model. It features 48 SPUs as well as 16 Texture Address Units and 8 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce GT 315		52 Watts
	Difference: 37 Watts (247%)

Memory Bandwidth

As far as performance goes, the GeForce GT 315 should theoretically be a lot superior to the GeForce 820M in general. (explain)

GeForce GT 315		25280 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 9280 (58%)

Texel Rate

The GeForce 820M will be a little bit (approximately 15%) more effective at AF than the GeForce GT 315. (explain)

GeForce 820M		11504 Mtexels/sec
GeForce GT 315		10000 Mtexels/sec
	Difference: 1504 (15%)

Pixel Rate

The GeForce GT 315 should be quite a bit (about 74%) faster with regards to AA than the GeForce 820M, and able to handle higher resolutions better. (explain)

GeForce GT 315		5000 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 2124 (74%)

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 largest amount of data (in units of megabytes per second) that can be transferred past the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.