GeForce 820M vs Radeon HD 4850 X2 512MB

Intro

Compare all of that to the Radeon HD 4850 X2 512MB, which comes with a GPU core clock speed of 625 MHz, and 512 MB of GDDR3 RAM set to run at 993 MHz through a 256-bit bus. It also features 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 235 Watts (1567%)

Memory Bandwidth

Performance-wise, the Radeon HD 4850 X2 512MB should in theory be much superior to the GeForce 820M overall. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 111104 (694%)

Texel Rate

The Radeon HD 4850 X2 512MB will be a lot (more or less 335%) faster with regards to texture filtering than the GeForce 820M. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 38496 (335%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 4850 X2 512MB is superior to the GeForce 820M, and very much so. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 17124 (595%)

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: Memory bandwidth is the largest amount of data (counted in MB per second) that can be transported across the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, 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 number of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels the video 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 ROPs by the clock speed of the card. 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 fill rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.