GeForce 8600 GT 256MB GDDR3 vs Radeon HD 7990

Intro

Compare those specs to the Radeon HD 7990, which comes with GPU clock speed of 950 MHz, and 3072 MB of GDDR5 RAM running at 1500 MHz through a 384-bit bus. It also is made up of 2048 SPUs, 128 TAUs, 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 7990		375 Watts
	Difference: 328 Watts (698%)

Memory Bandwidth

The Radeon HD 7990 should theoretically be much faster than the GeForce 8600 GT 256MB GDDR3 overall. (explain)

Radeon HD 7990		576000 MB/sec
GeForce 8600 GT 256MB GDDR3		22400 MB/sec
	Difference: 553600 (2471%)

Texel Rate

The Radeon HD 7990 is much (approximately 2715%) more effective at AF than the GeForce 8600 GT 256MB GDDR3. (explain)

Radeon HD 7990		243200 Mtexels/sec
GeForce 8600 GT 256MB GDDR3		8640 Mtexels/sec
	Difference: 234560 (2715%)

Pixel Rate

The Radeon HD 7990 will be quite a bit (about 1307%) better at full screen anti-aliasing than the GeForce 8600 GT 256MB GDDR3, and able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 7990		60800 Mpixels/sec
GeForce 8600 GT 256MB GDDR3		4320 Mpixels/sec
	Difference: 56480 (1307%)

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: Bandwidth is the maximum amount of information (measured in MB per second) that can be transferred past the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory speed. If the card has DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, 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 applied per second. This is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can 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 ROPs by the the core clock speed. 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 max fill rate.