Radeon HD 4790 vs Radeon R5 M255

Intro

Compare that to the Radeon R5 M255, which has GPU core speed of 940 MHz, and 2048 MB of DDR3 RAM set to run at 1000 MHz through a 64-bit bus. It also features 320 SPUs, 20 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 4790 should be much faster than the Radeon R5 M255 overall. (explain)

Radeon HD 4790		102400 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 86400 (540%)

Texel Rate

The Radeon HD 4790 should be a bit (about 2%) better at AF than the Radeon R5 M255. (explain)

Radeon HD 4790		19200 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 400 (2%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 4790 is the winner, by a large margin. (explain)

Radeon HD 4790		9600 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 2080 (28%)

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: Bandwidth is the largest amount of data (measured in MB per second) that can be moved past the external memory interface in one second. It is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher 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 amount of texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total number of texture units 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 per second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.