Windows 10 – Windows 10 Does Not See Second CPU

Yes, a multi-core processor is a single piece of hardware ("one processor") that provides several cores than can work concurrently.

The i5 is a single processor that provides either 2 or 4 physical cores depending on model (see here).

Note that some Intel processors (the i5 included) use hyperthreading, a system where a single processor has (for example) 2 physical cores, but will provide 4 logical cores - allowing the operating system to treat the processor as having more cores than it really does.

Actually, no. A dual core processor is one processor with 2 cores, a quad core is one processor with 4 cores.. and so on.Hyperthreading dosen't come onto play yet

Lets take a 8 core processor, and have them on a hypothetical 8 processor SMP system. You have 8 processors with 64 physical cores . Hyperthreading lets you run 128 logical cores on them. Likewise the same setup with quadcores would have 8 processors with 32 physical cores, and with hyperthreading run up to 64 logical cores (which is the maximum in the windows server enterprise would be able to run).

Apparently in this case, a logical core is equivalent to the ability to run a thread.

EDIT: cleaned up the answer. Apparently i misunderstood it - the hyperthreading article on wikipedia was really useful here