How to retrieve processorID,Motherboard serial number and MAC address of a PC in C#.net

Add using System.Management; namespace in your application (You can find it in :
Reference -> Add reference -> .NET tab -> System.management).

using System.Management;

On Page_Load Event add the following code:-

ManagementObjectSearcher MOS = new ManagementObjectSearcher("Select * From Win32_BaseBoard");
foreach (ManagementObject getserial in MOS.Get())
{
ltrSerialNumber.Text = getserial["SerialNumber"].ToString();
// Listout all information
GridView1.DataSource = getserial.Properties;
GridView1.DataBind();
}

//Code for retrieving Processor's Identity
MOS = new ManagementObjectSearcher("Select * From Win32_processor");
foreach (ManagementObject getPID in MOS.Get())
{
ltrProcessorID.Text = getPID["ProcessorID"].ToString();
// Listout all information
GridView2.DataSource = getPID.Properties;
GridView2.DataBind();
}

//Code for retrieving Network Adapter Configuration
MOS = new ManagementObjectSearcher("Select * From Win32_NetworkAdapterConfiguration");
foreach (ManagementObject mac in MOS.Get())
{
ltrMACAddress.Text = mac["MACAddress"].ToString();
// Listout all information
GridView3.DataSource = mac.Properties;
GridView3.DataBind();
}