Radeon HD 4650 1GB vs Radeon HD 7770

Intro

Compare those specifications to the Radeon HD 7770, which features clock speeds of 1000 MHz on the GPU, and 1125 MHz on the 1024 MB of GDDR5 RAM. It features 640 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 1GB		55 Watts
Radeon HD 7770		80 Watts
	Difference: 25 Watts (45%)

Memory Bandwidth

The Radeon HD 7770 should theoretically perform much faster than the Radeon HD 4650 1GB in general. (explain)

Radeon HD 7770		72000 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 49600 (221%)

Texel Rate

The Radeon HD 7770 is much (approximately 108%) more effective at anisotropic filtering than the Radeon HD 4650 1GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4650 1GB		19200 Mtexels/sec
	Difference: 20800 (108%)

Pixel Rate

The Radeon HD 7770 should be a lot (about 233%) faster with regards to full screen anti-aliasing than the Radeon HD 4650 1GB, and also should be capable of handling higher resolutions without slowing down too much. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4650 1GB		4800 Mpixels/sec
	Difference: 11200 (233%)

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 data (measured in megabytes per second) that can be transferred past the external memory interface in one second. The number is worked out by multiplying the card's bus width by its memory speed. In the case of DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This number is worked out by multiplying the total number of texture units 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 applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on lots of 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.