For a range of cells, use this Change event instead of the one I gave you earlier...
Private Sub Worksheet_Change(ByVal Target As Range)
  Dim Rng As Range, Cell As Range
  Set Rng = Intersect(Target, Range("C5:AG5"))
  If Not Rng Is Nothing Then
    Application.EnableEvents = False
    For Each Cell In Rng
      Cell.Value = UCase(Cell.Value)
    Next
    Application.EnableEvents = True
  End If
End Sub