GeForce 8600 GT 256MB GDDR3 vs Radeon HD 7870

Intro

Compare that to the Radeon HD 7870, which comes with a clock frequency of 1000 MHz and a GDDR5 memory speed of 1200 MHz. It also uses a 256-bit bus, and uses a 28 nm design. It is comprised of 1280 SPUs, 80 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 256MB GDDR3		47 Watts
Radeon HD 7870		175 Watts
	Difference: 128 Watts (272%)

Memory Bandwidth

As far as performance goes, the Radeon HD 7870 should theoretically be quite a bit better than the GeForce 8600 GT 256MB GDDR3 overall. (explain)

Radeon HD 7870		153600 MB/sec
GeForce 8600 GT 256MB GDDR3		22400 MB/sec
	Difference: 131200 (586%)

Texel Rate

The Radeon HD 7870 will be a lot (approximately 826%) more effective at texture filtering than the GeForce 8600 GT 256MB GDDR3. (explain)

Radeon HD 7870		80000 Mtexels/sec
GeForce 8600 GT 256MB GDDR3		8640 Mtexels/sec
	Difference: 71360 (826%)

Pixel Rate

The Radeon HD 7870 will be a lot (about 641%) faster with regards to AA than the GeForce 8600 GT 256MB GDDR3, and should be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 7870		32000 Mpixels/sec
GeForce 8600 GT 256MB GDDR3		4320 Mpixels/sec
	Difference: 27680 (641%)

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 information (measured in MB per second) that can be moved past the external memory interface within a second. The number is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type memory, it should 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, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.