GeForce GTX 980M vs Radeon HD 4890 1GB

Intro

Compare those specifications to the Radeon HD 4890 1GB, which has a clock speed of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also uses a 256-bit memory bus, and makes use of a 55 nm design. It is comprised of 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 GTX 980M		100 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 90 Watts (90%)

Memory Bandwidth

In theory, the GeForce GTX 980M will be 3% faster than the Radeon HD 4890 1GB overall, due to its greater data rate. (explain)

GeForce GTX 980M		128000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 3200 (3%)

Texel Rate

The GeForce GTX 980M will be quite a bit (about 149%) better at texture filtering than the Radeon HD 4890 1GB. (explain)

GeForce GTX 980M		99648 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 59648 (149%)

Pixel Rate

The GeForce GTX 980M is quite a bit (about 315%) faster with regards to AA than the Radeon HD 4890 1GB, and also should be capable of handling higher screen resolutions without slowing down too much. (explain)

GeForce GTX 980M		66432 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 50432 (315%)

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 (measured in MB per second) that can be moved past the external memory interface in one second. The number is worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.