public class DeviceMonitor
    {

        static readonly PerformanceCounter cpuCounter = new PerformanceCounter("Processor", "% Processor Time", "_Total");
        static readonly PerformanceCounter ramCounter = new PerformanceCounter("Memory", "Available MBytes");
        static readonly PerformanceCounter uptime = new PerformanceCounter("System", "System Up Time");


        public static bool GetInternetAvilable()
        {
            bool networkUp = System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable();
            return networkUp;
        }

        public static TimeSpan GetSystemUpTime()
        {
            uptime.NextValue();
            TimeSpan ts = TimeSpan.FromSeconds(uptime.NextValue());
            return ts;
        }

        public static string GetPhysicalMemory()
        {
            string str = null;
            ManagementObjectSearcher objCS = new ManagementObjectSearcher("SELECT * FROM Win32_ComputerSystem");
            foreach (ManagementObject objMgmt in objCS.Get())
            {
                str = objMgmt["totalphysicalmemory"].ToString();
            }
            return str;
        }

        public static string getCurrentCpuUsage()
        {
            return cpuCounter.NextValue() + "%";
        }

        public static string getAvailableRAM()
        {
            return ramCounter.NextValue() + "MB";
        }
    }

c#獲取電腦運行狀態（cpu,內存，網絡，系統運行時間）