Question

Currently I am using:

ManagementObjectSearcher searcher = 
                   new ManagementObjectSearcher("Select * FROM WIN32_Processor");
ManagementObjectCollection mObject = searcher.Get();

foreach (ManagementObject obj in mObject)
{
  var architecture = obj.GetPropertyValue("Architecture");
}

architecture = 0

This article shows that 0 means x86

The processor that the computer is running is intel core 2 duo E7500

OS is Windows XP 32 bit

CPU-Z shows

Is there a way to determine if a Windows XP computer has a processor that supports 64bit?

Answer 1

It may not be ideal, but it’s relatively straightforward to create a (native) DLL using VC++ or the like and query the processor’s features directly. This method could then be PInvoked from your C# application.

The following C++ method would return true when run on a 64 bit capable processor, and false on a 32 bit only processor (whether the OS is 32 or 64 bit):

bool __declspec(naked) IsCPU64BitCapable()
{
    __asm
    {
        // Save EBX since it's affected by CPUID
        push ebx
        // Determine whether the CPU supports retrieving extended feature data
        mov eax, 0x80000000
        cpuid
        cmp eax, 0x80000000
        // No extended data => no 64 bit
        jbe no_extended_data
        // Request extended feature data
        mov eax, 0x80000001
        cpuid
        // Bit 29 of EDX will now indicate whether the CPU is 64 bit capable
        mov eax, edx
        shr eax, 29
        and eax, 1
        jmp extended_data
    no_extended_data:
        xor eax,eax
    extended_data:
        // Restore EBX
        pop ebx
        ret
    }
}

This method can then be used from C# using:

[DllImport("Test64Bit.dll")]
private static extern bool IsCPU64BitCapable();