GeForce 820M vs Radeon HD 4890 2GB

Intro

Compare those specs to the Radeon HD 4890 2GB, which comes with a clock frequency of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also uses a 256-bit bus, and makes use of a 55 nm design. It is comprised of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 175 Watts (1167%)

Memory Bandwidth

The Radeon HD 4890 2GB should theoretically perform a lot faster than the GeForce 820M overall. (explain)

Radeon HD 4890 2GB		124800 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 108800 (680%)

Texel Rate

The Radeon HD 4890 2GB is quite a bit (more or less 248%) more effective at anisotropic filtering than the GeForce 820M. (explain)

Radeon HD 4890 2GB		40000 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 28496 (248%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 4890 2GB is a better choice, by far. (explain)

Radeon HD 4890 2GB		16000 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 13124 (456%)

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 largest amount of information (counted in megabytes per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the interface width by its memory speed. In the case of DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill 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 ability to reach the maximum fill rate.