Radeon HD 4650 1GB vs Radeon HD 7850

Intro

Compare those specs to the Radeon HD 7850, which features a GPU core clock speed of 860 MHz, and 2048 MB of GDDR5 RAM running at 1200 MHz through a 256-bit bus. It also features 1024 Stream Processors, 64 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 1GB		55 Watts
Radeon HD 7850		130 Watts
	Difference: 75 Watts (136%)

Memory Bandwidth

The Radeon HD 7850 should theoretically perform quite a bit faster than the Radeon HD 4650 1GB overall. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 131200 (586%)

Texel Rate

The Radeon HD 7850 will be quite a bit (approximately 187%) better at texture filtering than the Radeon HD 4650 1GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4650 1GB		19200 Mtexels/sec
	Difference: 35840 (187%)

Pixel Rate

The Radeon HD 7850 should be a lot (approximately 473%) faster with regards to FSAA than the Radeon HD 4650 1GB, and will be able to handle higher screen resolutions while still performing well. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4650 1GB		4800 Mpixels/sec
	Difference: 22720 (473%)

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 (measured in MB per second) that can be transported past the external memory interface in a second. It is calculated by multiplying the bus width by its memory speed. If the card has DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total texture units by the core speed of the chip. The better this number, 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 maximum amount of pixels the video card could possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.