program CPUSpeed;
uses SysUtils, windows;

function CPUSpd: String;
const
 DelayTime = 500; // measure time in ms
var
 TimerHi, TimerLo: DWORD;
 PriorityClass, Priority: Integer;
begin
    PriorityClass :=GetPriorityClass(GetCurrentProcess);
    Priority := GetThreadPriority(GetCurrentThread);
    SetPriorityClass(GetCurrentProcess,REALTIME_PRIORITY_CLASS);
    SetThreadPriority(GetCurrentThread,THREAD_PRIORITY_TIME_CRITICAL);

    Sleep(10);

    asm
       dw 310Fh // rdtsc
       mov TimerLo, eax
       mov TimerHi, edx
    end;

    Sleep(DelayTime);

    asm
       dw 310Fh // rdtsc
       sub eax, TimerLo
       sbb edx, TimerHi
       mov TimerLo, eax
       mov TimerHi, edx
    end;

    SetThreadPriority(GetCurrentThread, Priority);
    SetPriorityClass(GetCurrentProcess, PriorityClass);
    Result := IntToStr(Round(TimerLo / (1000.0 * DelayTime)));
end;


begin
 MessageBox(0,PChar('CPU speed is '+CPUSpd+' MHz'),'CPU Speed Check',MB_IconInformation+MB_OK);
end.