GeForce GTS 250 1GB vs Radeon HD 4870 1GB

Intro

Compare that to the Radeon HD 4870 1GB, which comes with a core clock frequency of 750 MHz and a GDDR5 memory frequency of 900 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTS 250 1GB		145 Watts
Radeon HD 4870 1GB		150 Watts
	Difference: 5 Watts (3%)

Memory Bandwidth

In theory, the Radeon HD 4870 1GB should be 64% quicker than the GeForce GTS 250 1GB overall, due to its higher data rate. (explain)

Radeon HD 4870 1GB		115200 MB/sec
GeForce GTS 250 1GB		70400 MB/sec
	Difference: 44800 (64%)

Texel Rate

The GeForce GTS 250 1GB will be a lot (about 57%) faster with regards to anisotropic filtering than the Radeon HD 4870 1GB. (explain)

GeForce GTS 250 1GB		47232 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 17232 (57%)

Pixel Rate

The Radeon HD 4870 1GB is just a bit (about 2%) more effective at full screen anti-aliasing than the GeForce GTS 250 1GB, and also able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 4870 1GB		12000 Mpixels/sec
GeForce GTS 250 1GB		11808 Mpixels/sec
	Difference: 192 (2%)

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 max amount of data (in units of megabytes per second) that can be transported past the external memory interface in one second. The number is worked out by multiplying the interface width by the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. 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 texture map elements (texels) that are processed per second. This is worked out by multiplying the total number of texture units by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.