Radeon HD 4750 vs Radeon HD 6790

Intro

Compare all of that to the Radeon HD 6790, which uses a 40 nm design. AMD has clocked the core speed at 840 MHz. The GDDR5 memory is set to run at a frequency of 1050 MHz on this particular model. It features 800 SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4750		75 Watts
Radeon HD 6790		150 Watts
	Difference: 75 Watts (100%)

Memory Bandwidth

Theoretically, the Radeon HD 6790 should perform a lot faster than the Radeon HD 4750 in general. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4750		51200 MB/sec
	Difference: 83200 (163%)

Texel Rate

The Radeon HD 6790 should be much (approximately 44%) more effective at AF than the Radeon HD 4750. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4750		23360 Mtexels/sec
	Difference: 10240 (44%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6790 is a better choice, but not by far. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4750		11680 Mpixels/sec
	Difference: 1760 (15%)

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 maximum amount of information (in units of MB per second) that can be moved over the external memory interface in one second. The number is calculated by multiplying the card's bus width by its memory speed. If the card has DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster 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 texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.