Radeon HD 4650 512MB vs Radeon HD 6870

Intro

Compare all that to the Radeon HD 6870, which makes use of a 40 nm design. AMD has clocked the core speed at 900 MHz. The GDDR5 RAM works at a frequency of 1050 MHz on this specific card. It features 1120 SPUs along with 56 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 6870		151 Watts
	Difference: 96 Watts (175%)

Memory Bandwidth

The Radeon HD 6870 should theoretically be quite a bit faster than the Radeon HD 4650 512MB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 118400 (740%)

Texel Rate

The Radeon HD 6870 should be quite a bit (more or less 163%) faster with regards to AF than the Radeon HD 4650 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 31200 (163%)

Pixel Rate

The Radeon HD 6870 should be much (approximately 500%) better at FSAA than the Radeon HD 4650 512MB, and also will be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 24000 (500%)

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 largest amount of data (counted in megabytes per second) that can be transported over the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, the result 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 AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the core 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 is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.