어느? 팁에서 가져온 함수 입니다.

테스트는 안해봤지만 되리라 믿고 올립니다. ^^

function SetPCSystemTime(tDati: TDateTime): Boolean;
var
tSetDati: TDateTime;
vDatiBias: Variant;
tTZI: TTimeZoneInformation;
tST: TSystemTime;
begin
GetTimeZoneInformation(tTZI);
vDatiBias := tTZI.Bias / 1440;
tSetDati := tDati + vDatiBias;
With tST do
begin
   wYear   := StrToInt(FormatDateTime('yyyy', tSetDati));
   wMonth  := StrToInt(FormatDateTime('mm',   tSetDati));
   wDay    := StrToInt(FormatDateTime('dd',   tSetDati));
   wHour   := StrToInt(FormatDateTime('hh',   tSetDati));
   wMinute := StrToInt(FormatDateTime('nn',   tSetDati));
   wSecond := StrToInt(FormatDateTime('ss',   tSetDati));
   wMilliseconds := 0;
end;
SetPCSystemTime := SetSystemTime(tST);
end;