GeForce 8400 GS 512MB vs GeForce GT 420

Intro

Compare all of that to the GeForce GT 420, which makes use of a 40 nm design. nVidia has set the core speed at 700 MHz. The GDDR3 RAM is set to run at a frequency of 900 MHz on this model. It features 48 SPUs along with 8 TAUs and 4 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8400 GS 512MB		40 Watts
GeForce GT 420		50 Watts
	Difference: 10 Watts (25%)

Memory Bandwidth

Theoretically speaking, the GeForce GT 420 should perform a lot faster than the GeForce 8400 GS 512MB overall. (explain)

GeForce GT 420		28800 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 22400 (350%)

Texel Rate

The GeForce GT 420 will be just a bit (more or less 8%) more effective at anisotropic filtering than the GeForce 8400 GS 512MB. (explain)

GeForce GT 420		5600 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 400 (8%)

Pixel Rate

The GeForce GT 420 is a bit (about 8%) better at full screen anti-aliasing than the GeForce 8400 GS 512MB, and will be capable of handling higher screen resolutions while still performing well. (explain)

GeForce GT 420		2800 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 200 (8%)

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 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 interface width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, 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 texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at handling 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 chip could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out 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 many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.