Radeon HD 4650 1GB vs Radeon HD 6790

Intro

Compare that to the Radeon HD 6790, which has a GPU core clock speed of 840 MHz, and 1024 MB of GDDR5 RAM running at 1050 MHz through a 256-bit bus. It also features 800 Stream Processors, 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 4650 1GB		55 Watts
Radeon HD 6790		150 Watts
	Difference: 95 Watts (173%)

Memory Bandwidth

The Radeon HD 6790 should theoretically perform quite a bit faster than the Radeon HD 4650 1GB in general. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 112000 (500%)

Texel Rate

The Radeon HD 6790 should be much (about 75%) more effective at anisotropic filtering than the Radeon HD 4650 1GB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4650 1GB		19200 Mtexels/sec
	Difference: 14400 (75%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 6790 is the winner, by a large margin. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4650 1GB		4800 Mpixels/sec
	Difference: 8640 (180%)

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 data (in units of MB per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the bus width by its memory clock speed. If the card has DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high 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 amount of texture units of the card by the core clock speed of the chip. The better this number, the better the card will be at handling 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 the video card could possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.