Radeon HD 3650 256MB vs Radeon HD 4650 1GB

Intro

Compare those specs to the Radeon HD 4650 1GB, which uses a 55 nm design. AMD has set the core frequency at 600 MHz. The GDDR3 RAM works at a speed of 700 MHz on this specific card. It features 320(64x5) SPUs along with 32 TAUs 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 perform a little 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%) more effective at AF 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: Memory bandwidth is the maximum amount of information (in units of megabytes per second) that can be moved past the external memory interface in a second. It's worked out by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, 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 number of 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 better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines 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, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.