Radeon HD 4650 512MB vs Radeon HD 7850

Intro

Compare those specifications to the Radeon HD 7850, which has a core clock frequency of 860 MHz and a GDDR5 memory speed of 1200 MHz. It also uses a 256-bit memory bus, and makes use of a 28 nm design. It is comprised of 1024 SPUs, 64 TAUs, and 32 ROPs.

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 should in theory 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 quite a bit (more or less 187%) more effective at AF 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

The Radeon HD 7850 should be quite a bit (about 473%) better at AA than the Radeon HD 4650 512MB, and should be capable of handling higher resolutions better. (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 max amount of information (counted in megabytes per second) that can be transferred across the external memory interface in one second. The number is worked out by multiplying the bus width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total number of texture units by the core speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.