Radeon HD 4550 256MB vs Radeon HD 6790

Intro

Compare those specs to the Radeon HD 6790, which features a clock frequency of 840 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 256-bit memory bus, and uses a 40 nm design. It is comprised of 800 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4550 256MB		25 Watts
Radeon HD 6790		150 Watts
	Difference: 125 Watts (500%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6790 should be 950% faster than the Radeon HD 4550 256MB overall, due to its greater data rate. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4550 256MB		12800 MB/sec
	Difference: 121600 (950%)

Texel Rate

The Radeon HD 6790 will be a lot (approximately 600%) more effective at texture filtering than the Radeon HD 4550 256MB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4550 256MB		4800 Mtexels/sec
	Difference: 28800 (600%)

Pixel Rate

The Radeon HD 6790 should be much (more or less 460%) faster with regards to anti-aliasing than the Radeon HD 4550 256MB, and able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4550 256MB		2400 Mpixels/sec
	Difference: 11040 (460%)

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 a second. It's worked out by multiplying the interface width by its memory speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, 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 amount of texture map elements (texels) that are processed per second. This number is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.