GeForce GT 420 vs Radeon HD 4870 X2

Intro

Compare that to the Radeon HD 4870 X2, which has a GPU core clock speed of 750 MHz, and 1024 MB of GDDR5 RAM set to run at 900 MHz through a 256-bit bus. It also features 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 300 Watts (600%)

Memory Bandwidth

As far as performance goes, the Radeon HD 4870 X2 should in theory be quite a bit better than the GeForce GT 420 overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 201600 (700%)

Texel Rate

The Radeon HD 4870 X2 should be quite a bit (approximately 971%) faster with regards to anisotropic filtering than the GeForce GT 420. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 54400 (971%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 4870 X2 is the winner, by far. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 21200 (757%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of data (measured in MB per second) that can be moved across the external memory interface in one second. The number is worked out by multiplying the bus width by the speed of its memory. If the card has DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This number is worked out by multiplying the total texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card 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 sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.