GeForce GT 420 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 memory. It features 640 SPUs as well as 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
Radeon HD 7770		80 Watts
	Difference: 30 Watts (60%)

Memory Bandwidth

Theoretically, the Radeon HD 7770 should be a lot faster than the GeForce GT 420 in general. (explain)

Radeon HD 7770		72000 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 43200 (150%)

Texel Rate

The Radeon HD 7770 will be a lot (about 614%) faster with regards to AF than the GeForce GT 420. (explain)

Radeon HD 7770		40000 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 34400 (614%)

Pixel Rate

The Radeon HD 7770 should be a lot (approximately 471%) more effective at AA than the GeForce GT 420, and should be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 7770		16000 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 13200 (471%)

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 over the external memory interface in a second. It is worked out by multiplying the interface width by its memory clock speed. In the case of DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster 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 is worked out by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on quite a few 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.