Radeon HD 4790 vs Radeon R9 M275X

Intro

Compare those specs to the Radeon R9 M275X, which makes use of a 28 nm design. AMD has clocked the core frequency at 900 MHz. The GDDR5 memory is set to run at a frequency of 1125 MHz on this particular model. It features 640 SPUs as well as 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 4790, in theory, should be much faster than the Radeon R9 M275X overall. (explain)

Radeon HD 4790		102400 MB/sec
Radeon R9 M275X		72000 MB/sec
	Difference: 30400 (42%)

Texel Rate

The Radeon R9 M275X is much (about 88%) better at AF than the Radeon HD 4790. (explain)

Radeon R9 M275X		36000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 16800 (88%)

Pixel Rate

The Radeon R9 M275X should be much (more or less 50%) more effective at anti-aliasing than the Radeon HD 4790, and able to handle higher screen resolutions more effectively. (explain)

Radeon R9 M275X		14400 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 4800 (50%)

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 maximum amount of data (measured in megabytes per second) that can be transported over the external memory interface in a second. The number is calculated by multiplying the bus width by its memory clock speed. If the card has DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher this number, 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 most pixels the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.