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Inside the Intel Sandy Bridge Microarchitecture


The Integrated Graphics Engine

The graphics processor integrated in Sandy Bridge-based processors will have a DirectX 10.1 engine. As explained in the first page of this tutorial, it will be available in the same silicon chip as the rest of the CPU, instead of being available at a separate chip but “glued” together with the CPU inside the same package.

In Figure 8, you have an overall look at the Sandy Bridge graphics processor.

Sandy BridgeFigure 8: Sandy Bridge graphics processor

The number of execution units (“processors”) will depend on the CPU (e.g. Core i5 CPUs will have more execution units than Core i3 parts). Sandy Bridge processors can have up to 12 graphics execution units.

If you pay close attention in Figure 8, you will see that “Display” and “Graphics” are in separate parts of the CPU. This can be read as “2D” and “3D,” and helps the CPU to save energy by turning off the graphics processor when you are not playing games.

Another important innovation is that the graphics engine can use the Last Level Cache (LLC, formerly known as L3 memory cache) to store data, especially textures. This improves 3D performance, as the graphics engine doesn’t need to go to the RAM to fetch for data, it can load data directly from the cache (if it is already there, of course).