GeForce GT 420 vs GeForce GTS 150

Intro

Compare those specifications to the GeForce GTS 150, which comes with a clock speed of 740 MHz and a GDDR3 memory frequency of 500 MHz. It also features a 256-bit memory bus, and uses a 55 nm design. It is made up of 128 SPUs, 64 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
GeForce GTS 150		141 Watts
	Difference: 91 Watts (182%)

Memory Bandwidth

Theoretically speaking, the GeForce GTS 150 will be 11% faster than the GeForce GT 420 in general, due to its greater bandwidth. (explain)

GeForce GTS 150		32000 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 3200 (11%)

Texel Rate

The GeForce GTS 150 is a lot (about 746%) more effective at texture filtering than the GeForce GT 420. (explain)

GeForce GTS 150		47360 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 41760 (746%)

Pixel Rate

The GeForce GTS 150 will be quite a bit (more or less 323%) better at FSAA than the GeForce GT 420, and also will be capable of handling higher resolutions more effectively. (explain)

GeForce GTS 150		11840 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 9040 (323%)

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 max amount of information (counted in MB per second) that can be moved over the external memory interface in a second. The number is worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the 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 amount of texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.