private void OnTimerElapsed(object sender, ElapsedEventArgs e) { List <double> cpuTemp = CpuGraphPoints.ToList(); List <double> memoryTemp = MemoryGraphPoints.ToList(); cpuTemp.Add(_monitor.GetCPURate()); memoryTemp.Add(_monitor.GetMemoryRate()); if (cpuTemp.Count > 61) { cpuTemp.RemoveRange(0, cpuTemp.Count - 61); } if (memoryTemp.Count > 61) { memoryTemp.RemoveRange(0, memoryTemp.Count - 61); } CpuGraphPoints = new ObservableCollection <double>(cpuTemp); MemoryGraphPoints = new ObservableCollection <double>(memoryTemp); }