...
var
  th: cardinal;
  h1: integer;
...
/////Округление дробей
function RoundEx(X: Double; Precision: Integer): Double;
{ Precision : 1 - до целых, 10 - до десятых, 100 - до сотых... }
var
  ScaledFractPart, Temp: Double;
begin
  ScaledFractPart := Frac(X) * Precision;
  Temp := Frac(ScaledFractPart);
  ScaledFractPart := Int(ScaledFractPart);
  if Temp >= 0.5 then ScaledFractPart := ScaledFractPart + 1;
  if Temp <= -0.5 then ScaledFractPart := ScaledFractPart - 1;
  RoundEx := Int(X) + ScaledFractPart / Precision;
end;

/////// CPU CLOCK
function RdTSC : int64; register;
asm
  db $0f, $31
end;

function GetCyclesPerSecond : double;
var
  hF, T, et, sc : int64;
begin
  QueryPerformanceFrequency(hF); // HiTicks / second
  QueryPerformanceCounter(T); // Determine start HiTicks
  et := T + hF; // (Cycles are passing, but we can still USE them!)
  sc := RdTSC; // Get start cycles
  repeat // Use Hi Perf Timer to loop for 1 second
    QueryPerformanceCounter(T); // Check ticks NOW
  until (T >= et); // Break the moment we equal or exceed et
    Result := (RdTSC - sc) / 1000000; // Get stop cycles and calculate result
end;

procedure cpuclockinfo;
begin
form1.cpuclock.Text:=double2str(RoundEx(GetCyclesPerSecond,1000))+' Mhz';
end;

procedure TForm1.Timer1Timer(Sender: PObj);
begin
h1 := beginthread(nil, 1024, @cpuclockinfo, nil, 0, th);
end;

procedure TForm1.CheckBox1Click(Sender: PObj);
begin
if checkbox1.Checked=true then
timer1.Enabled:=true else begin
timer1.Enabled:=false;
terminatethread(h1, 0) end;
end;