Answer by djmoore711 · Aug 31, 2010 at 05:07 AM
You could think of it as the buffer for your CPU, between the RAM and the CPU. Technically it's now in front of the North Bridge now, but nontheless, it's a very high-speed buffer for the CPU. You can now see how having a bigger cache on the CPU is better. Other than speed, this is usually a driving cost behind any CPU. It is extremely fast memory. The more threads you have (pipelines) they more you may need. Normal chips come with L1, L2, and L3; each one is bigger, and due to this size, is slower, also. Data flows from RAM > North Bridge > L3 > L2 > L1 > CPU.
For example, on the new Intel Core i7: L1 (32KB per core Instruction, 32KB per core Data), L2 (256KB per core Instruction and Data), L3 (Up to 8MB used for all applications).
Hope that helps.
Answer by kevin · Aug 31, 2010 at 01:21 AM
L3 keeps copies of requested items in case a different core makes a subsequent request. The advantage of having on-board cache is that itâ€™s faster, more efficient and less expensive than placing separate cache on the motherboard.
More info at http://www.wisegeek.com/what-is-l3-cache.htm
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