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I recently purchased an Intel i5-650 processor. On the Intel site, this the technical specifications show that the processor should only have two cores.

http://www.intel.com/products/processor/corei5/specifications.htm

However, when I check the Performance tab in 'Windows Task Manager', it shows 4 sections under 'CPU Usage history', indicating 4 cores. Can someone confirm if I have two or four cores.

I have seen this behavior with two of my friends Intel i3 processors as well.

Thanks

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What you are seeing is hyper-threading. This enables a single core to process 2 concurrent threads of execution. http://en.wikipedia.org/wiki/Hyper-threading Its not actually as good as having 4 cores, but it provides a speedup.

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although the speedup varies significantly depending on the workload, you may expect about 30% speedup in total processor throughput (i.e. it's like having 2.6 cores) – netvope Nov 29 '10 at 6:24

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