Radeon HD 3650 256MB vs Radeon HD 4650 1GB

Intro

Compare those specifications to the Radeon HD 4650 1GB, which comes with core speeds of 600 MHz on the GPU, and 700 MHz on the 1024 MB of GDDR3 memory. It features 320(64x5) SPUs along with 32 Texture Address Units and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 1GB		55 Watts
Radeon HD 3650 256MB		78 Watts
	Difference: 23 Watts (42%)

Memory Bandwidth

The Radeon HD 3650 256MB should in theory be a bit faster than the Radeon HD 4650 1GB overall. (explain)

Radeon HD 3650 256MB		25600 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 3200 (14%)

Texel Rate

The Radeon HD 4650 1GB is a lot (about 231%) better at texture filtering than the Radeon HD 3650 256MB. (explain)

Radeon HD 4650 1GB		19200 Mtexels/sec
Radeon HD 3650 256MB		5800 Mtexels/sec
	Difference: 13400 (231%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 4650 1GB is a better choice, by a large margin. (explain)

Radeon HD 4650 1GB		4800 Mpixels/sec
Radeon HD 3650 256MB		2900 Mpixels/sec
	Difference: 1900 (66%)

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 maximum amount of information (in units of megabytes per second) that can be transferred past the external memory interface in a second. The number is calculated by multiplying the card's interface width by its memory speed. If it uses DDR memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.