Radeon HD 4650 1GB vs Radeon HD 6670 (OEM) 1GB

Intro

Compare those specs to the Radeon HD 6670 (OEM) 1GB, which has a clock speed of 800 MHz and a GDDR5 memory frequency of 1000 MHz. It also uses a 128-bit memory bus, and uses a 40 nm design. It features 480 SPUs, 24 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 1GB		55 Watts
Radeon HD 6670 (OEM) 1GB		63 Watts
	Difference: 8 Watts (15%)

Memory Bandwidth

In theory, the Radeon HD 6670 (OEM) 1GB should be 186% faster than the Radeon HD 4650 1GB overall, because of its greater bandwidth. (explain)

Radeon HD 6670 (OEM) 1GB		64000 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 41600 (186%)

Texel Rate

Both cards have the exact same texel rate, so in theory they should perform equally good at at anisotropic filtering. (explain)

Pixel Rate

The Radeon HD 6670 (OEM) 1GB should be a lot (more or less 33%) better at FSAA than the Radeon HD 4650 1GB, and also capable of handling higher resolutions without slowing down too much. (explain)

Radeon HD 6670 (OEM) 1GB		6400 Mpixels/sec
Radeon HD 4650 1GB		4800 Mpixels/sec
	Difference: 1600 (33%)

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 (measured in megabytes per second) that can be moved past the external memory interface in a second. It's calculated by multiplying the interface width by its memory speed. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied in one second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better this number, 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 the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.