How to detect CPU speed on Windows 64bit?

using System;
using System.Management;

namespace CpuSpeed
{
    class Program
    {
        static double? GetCpuSpeedInGHz()
        {
            double? GHz = null;
            using (ManagementClass mc = new ManagementClass("Win32_Processor"))
            {
                foreach (ManagementObject mo in mc.GetInstances())
                {
                    GHz = 0.001 * (UInt32) mo.Properties["CurrentClockSpeed"].Value;
                    break;
                }
            }
            return GHz;
        }

        static void Main(string[] args)
        {
            Console.WriteLine("The current CPU speed is {0}", (GetCpuSpeedInGHz() ?? -1.0).ToString());
            Console.ReadLine();
        }
    }
}

RegistryKey registrykeyHKLM = Registry.LocalMachine;
  string keyPath = @"HARDWAREDESCRIPTIONSystemCentralProcessor";
  RegistryKey registrykeyCPU = registrykeyHKLM.OpenSubKey(keyPath, false);
  string MHz = registrykeyCPU.GetValue("~MHz").ToString();
  string ProcessorNameString = (string)registrykeyCPU.GetValue("ProcessorNameString");
  registrykeyCPU.Close();
  registrykeyHKLM.Close();
  Console.WriteLine("{0} MHz for {1}", MHz, ProcessorNameString);

private float GetCpuClockSpeed()
{
    return (int) Registry.GetValue(@"HKEY_LOCAL_MACHINEHARDWAREDESCRIPTIONSystemCentralProcessor", "~MHz", 0);
}

Microsoft.Win32.RegistryKey registrykeyHKLM = Microsoft.Win32.Registry.LocalMachine;
string cpuPath = @"HARDWAREDESCRIPTIONSystemCentralProcessor";
Microsoft.Win32.RegistryKey registrykeyCPUs = registrykeyHKLM.OpenSubKey(cpuPath, false);
StringBuilder sbCPUDetails = new StringBuilder();
int iCPUCount;
for (iCPUCount = 0; iCPUCount < registrykeyCPUs.SubKeyCount; iCPUCount++)
{
    Microsoft.Win32.RegistryKey registrykeyCPUDetail = registrykeyHKLM.OpenSubKey(cpuPath + "\" + iCPUCount, false);
    string sMHz = registrykeyCPUDetail.GetValue("~MHz").ToString();
    string sProcessorNameString = registrykeyCPUDetail.GetValue("ProcessorNameString").ToString();
    sbCPUDetails.Append(Environment.NewLine + "t" + string.Format("CPU{0}: {1} MHz for {2}", new object[] { iCPUCount, sMHz, sProcessorNameString }));
    registrykeyCPUDetail.Close();
}
registrykeyCPUs.Close();
registrykeyHKLM.Close();
sCPUSpeed = iCPUCount++ + " core(s) found:" + sbCPUDetails.ToString();