GeForce GT 420 vs Radeon HD 7770

Intro

Compare all that to the Radeon HD 7770, which comes with a clock speed of 1000 MHz and a GDDR5 memory frequency of 1125 MHz. It also uses a 128-bit bus, and uses a 28 nm design. It is comprised of 640 SPUs, 40 TAUs, and 16 ROPs.

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

In theory, the Radeon HD 7770 should perform 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 should be a lot (about 614%) more effective at 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 will be much (approximately 471%) more effective at AA than the GeForce GT 420, and able to handle higher screen resolutions better. (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: Memory bandwidth is the maximum amount of information (in units of megabytes per second) that can be transported across the external memory interface in a second. It is worked out by multiplying the bus width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, 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 amount of texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total texture units by the core speed of the chip. The better this number, the better the graphics 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 most pixels that the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends 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 maximum fill rate.