Radeon HD 4650 512MB vs Radeon HD 7850

Intro

Compare that to the Radeon HD 7850, which comes with clock speeds of 860 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 memory. It features 1024 SPUs as well as 64 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 7850		130 Watts
	Difference: 75 Watts (136%)

Memory Bandwidth

The Radeon HD 7850, in theory, should perform quite a bit faster than the Radeon HD 4650 512MB in general. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 137600 (860%)

Texel Rate

The Radeon HD 7850 is much (about 187%) more effective at anisotropic filtering than the Radeon HD 4650 512MB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 35840 (187%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7850 is the winner, by far. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 22720 (473%)

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 information (measured in megabytes per second) that can be transferred across the external memory interface within a second. The number 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 it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This is worked out by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the graphics 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 chip could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the core 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 also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.