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 clocked the core speed at 700 MHz. The GDDR3 RAM works at a frequency of 900 MHz on this particular card. It features 48 SPUs along with 8 TAUs and 4 Rasterization Operator Units.

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 a small bit (approximately 8%) faster with regards to texture 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 will be just a bit (about 8%) better at AA than the GeForce 8400 GS 512MB, and also should be able to handle higher 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: Bandwidth is the maximum amount of data (counted in megabytes per second) that can be transported over the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 once 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 anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This is calculated by multiplying the total texture units by the core speed of the chip. The better this number, the better the 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 maximum amount of 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 amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill 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 max fill rate.