GeForce 820M vs Radeon HD 4870 512MB

Intro

Compare those specifications to the Radeon HD 4870 512MB, which uses a 55 nm design. AMD has clocked the core frequency at 750 MHz. The GDDR5 memory works at a speed of 900 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 135 Watts (900%)

Memory Bandwidth

The Radeon HD 4870 512MB should in theory perform much faster than the GeForce 820M overall. (explain)

Radeon HD 4870 512MB		115200 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 99200 (620%)

Texel Rate

The Radeon HD 4870 512MB is a lot (more or less 161%) faster with regards to texture filtering than the GeForce 820M. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 18496 (161%)

Pixel Rate

The Radeon HD 4870 512MB is quite a bit (more or less 317%) more effective at FSAA than the GeForce 820M, and also should be able to handle higher resolutions more effectively. (explain)

Radeon HD 4870 512MB		12000 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 9124 (317%)

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 max amount of information (counted in megabytes per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the bus width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the 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 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 speed of the chip. The higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs 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 fill rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.