I am trying to get the total installed ram

Question

I am trying to get the total installed memory. I have 6GB installed but this is returning 5.47GB. What can I do to fix this? I did a build on a x64 PC and am running the app on a x64 PC.

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
            internal class MEMORYSTATUSEX
            {
                public uint dwLength;
                public uint dwMemoryLoad;
                public ulong ullTotalPhys;
                public ulong ullAvailPhys;
                public ulong ullTotalPageFile;
                public ulong ullAvailPageFile;
                public ulong ullTotalVirtual;
                public ulong ullAvailVirtual;
                public ulong ullAvailExtendedVirtual;

                public MEMORYSTATUSEX()
                {
                    this.dwLength = (uint)Marshal.SizeOf(typeof(NativeMethods.MEMORYSTATUSEX));
                }
            }

            [return: MarshalAs(UnmanagedType.Bool)]
            [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
            internal static extern Boolean GlobalMemoryStatusEx([In, Out] MEMORYSTATUSEX lpBuffer);

public static String GetTotalRam
            {
                get
                {
                    ulong installedMemory = 0;
                    NativeMethods.MEMORYSTATUSEX memStatus = new NativeMethods.MEMORYSTATUSEX();
                    if (NativeMethods.GlobalMemoryStatusEx(memStatus))
                    {
                        installedMemory = memStatus.ullTotalPhys;
                    }
                    return ConvertBytes(installedMemory);
                }
            }

Answer 1

Your posted method gives you the total available memory, which is not exactly the same as the total installed memory.

To get the amount of installed memory, you can use a call to the GetPhysicallyInstalledSystemMemory function.

I think you'll find the Remarks section from that link interesting:

The GetPhysicallyInstalledSystemMemory function retrieves the amount of physically installed RAM from the computer's SMBIOS firmware tables. This can differ from the amount reported by the GlobalMemoryStatusEx function, which sets the ullTotalPhys member of the MEMORYSTATUSEX structure to the amount of physical memory that is available for the operating system to use. The amount of memory available to the operating system can be less than the amount of memory physically installed in the computer because the BIOS and some drivers may reserve memory as I/O regions for memory-mapped devices, making the memory unavailable to the operating system and applications.

EDIT: Added Sample code

Modified from the code found here :

[DllImport("kernel32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool GetPhysicallyInstalledSystemMemory(out long TotalMemoryInKilobytes);

static void Main()
{
    long memKb;
    GetPhysicallyInstalledSystemMemory(out memKb);
    Console.WriteLine((memKb / 1024 / 1024) + " GB of RAM installed.");
}

Answer 2

尽管这看起来很奇怪，但添加了对Microsoft.VisualBasic.dll的引用并使用此命令：

return new Microsoft.VisualBasic.Devices.ComputerInfo().TotalPhysicalMemory;