Radeon HD 4650 512MB vs Radeon HD 7870

Intro

Compare those specs to the Radeon HD 7870, which features a GPU core clock speed of 1000 MHz, and 2048 MB of GDDR5 memory set to run at 1200 MHz through a 256-bit bus. It also is made up of 1280 SPUs, 80 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 7870		175 Watts
	Difference: 120 Watts (218%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 should be quite a bit faster than the Radeon HD 4650 512MB overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 137600 (860%)

Texel Rate

The Radeon HD 7870 should be a lot (approximately 317%) more effective at texture filtering than the Radeon HD 4650 512MB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 60800 (317%)

Pixel Rate

The Radeon HD 7870 will be a lot (more or less 567%) better at AA than the Radeon HD 4650 512MB, and will be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 27200 (567%)

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 max amount of data (measured in megabytes per second) that can be moved past the external memory interface in one second. The number is worked out by multiplying the bus width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If it uses 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 texture map elements (texels) that are applied per second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number 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 - the lower the bandwidth is, the lower the potential to reach the max fill rate.