GeForce GT 420 vs Radeon HD 4850 X2 512MB

Intro

Compare those specs to the Radeon HD 4850 X2 512MB, which uses a 55 nm design. AMD has clocked the core frequency at 625 MHz. The GDDR3 memory is set to run at a speed of 993 MHz on this card. It features 800(160x5) SPUs as well as 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 200 Watts (400%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 X2 512MB will be 341% faster than the GeForce GT 420 in general, because of its higher data rate. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 98304 (341%)

Texel Rate

The Radeon HD 4850 X2 512MB will be quite a bit (about 793%) faster with regards to texture filtering than the GeForce GT 420. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 44400 (793%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 4850 X2 512MB is the winner, by a large margin. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 17200 (614%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the largest amount of data (in units of MB per second) that can be moved across the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory speed. If the card has DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This figure is calculated by multiplying the total number 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.