How to get remote machine Total RAM in C# / ASP.NET MVC

Question

I am building a Health & Monitoring page to show various servers CPU Usage and Memory Usage. Please advise how to get Total RAM so that I can show Memory Usage in %. I see lot of examples for local system but didn't find any working solution for remote machines.

CPU Usage:

var cpu = new PerformanceCounter("Processor", "% Processor Time", "_Total", server.Name);

Available Memory:

var rama = new PerformanceCounter("Memory", "Available MBytes", String.Empty, server.Name);

a = getCurrentCpuUsage();
Thread.Sleep(1000);
a = getCurrentCpuUsage();

b = getAvailableRAM();
Thread.Sleep(1000);
b = getAvailableRAM(); 

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

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

Tried to do something like below.

//System.Management.ManagementScope ms = new System.Management.ManagementScope(@"\\" + server.Name + @"\root\cimv2");
                    //System.Management.SelectQuery sq = new System.Management.SelectQuery("SELECT * FROM Win32_OperatingSystem");

                    //var wmiObject = new ManagementObjectSearcher(ms,sq);

                    //var memoryValues = wmiObject.Get().Cast<ManagementObject>().Select(mo => new
                    //{
                    //    FreePhysicalMemory = Double.Parse(mo["FreePhysicalMemory"].ToString()),
                    //    TotalVisibleMemorySize = Double.Parse(mo["TotalVisibleMemorySize"].ToString())
                    //}).FirstOrDefault();   

It didn't work though I impersonate user as ADMIN user on those servers. I am getting An exception of type 'System.UnauthorizedAccessException' occurred in System.Management.dll but was not handled in user code

Additional information: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

FYI.. Please note I can get all Server's Services data using the same ADMIN user access.

  var services = ServiceController.GetServices(server.Name);