This is our third purchase of a recertified Dell Optiplex 990 computer.  All three are performing well. After receiving this computer the first thing we did was to open the case and remove the DVD player and replace it with a DVD burner. The inside of the computer was pristine! No dust at all. The operating system - Windows 10 - was preinstalled. Of course it required updating but it was a painless process - and it registered itself. Our experience with recycled computers has been totally favorable. Save money and help the planet by using recycled computers.