How to get CPU's model number like Core i7-860 on Windows?

Open up "System Information" by

Start Menu > Accessories > System Tools > System Information

Then once in "System Information" open:

System Information > System Summary

On the right will be the "Processor", this will give you the full description of your CPU.

Windows Key + R will open the run command

Type CMD and press

Type wmic CPU get NAME and enter

For me it gives :

 Intel(R) Core(TM) i7 CPU  **920**  @ 2.67GHz

Where the 920 is what I think your looking for...
If its not, if you just type wmic CPU and press enter it will give you all the information about the processor in a hard to read fashion...
But then you can type wmic CPU get (whatever entry interests you) to get just that one.
Good Luck

You can check the Name Property of the Win32_Processor WMI class

Try this C# sample

using System;
using System.Collections.Generic;
using System.Management;
using System.Text;

namespace GetWMI_Info
{
    class Program
    {


        static void Main(string[] args)
        {
            try
            {
                string ComputerName = "localhost";
                ManagementScope Scope;                
                Scope = new ManagementScope(String.Format("\\\\{0}\\root\\CIMV2", ComputerName), null);
                Scope.Connect();
                ObjectQuery Query = new ObjectQuery("SELECT Name FROM Win32_Processor");
                ManagementObjectSearcher Searcher = new ManagementObjectSearcher(Scope, Query);
                foreach (ManagementObject WmiObject in Searcher.Get())
                {
                    Console.WriteLine("{0}",WmiObject["Name"]);                     
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(String.Format("Exception {0} Trace {1}",e.Message,e.StackTrace));
            }
            Console.WriteLine("Press Enter to exit");
            Console.Read();
        }
    }
}