Radeon HD 4650 512MB vs Radeon HD 7870

Intro

Compare all that to the Radeon HD 7870, which comes with a core clock speed of 1000 MHz and a GDDR5 memory frequency of 1200 MHz. It also features a 256-bit memory bus, and makes use of a 28 nm design. It is comprised of 1280 SPUs, 80 Texture Address Units, 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 7870		175 Watts
	Difference: 120 Watts (218%)

Memory Bandwidth

The Radeon HD 7870, in theory, should be quite a bit faster than the Radeon HD 4650 512MB in general. (explain)

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

Texel Rate

The Radeon HD 7870 is quite a bit (more or less 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 should be quite a bit (approximately 567%) better at FSAA than the Radeon HD 4650 512MB, and should be capable of handling higher 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: Memory bandwidth is the maximum amount of data (counted in MB per second) that can be moved past the external memory interface in a second. The number is worked out by multiplying the interface width by its memory speed. In the case of DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units 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 lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.