Daer all. I see here is a lot of discussions regarding installing second hard drive to Optiplex 160. Look: Regular hard drive 2.5' has thickness 9.5mm. SSD hard drives and slim factor HDDs have 7 mm thickness. I have turned in lags (2 mm) of a caddy in my Optiplex 160 and installed two drives: SSD and WD750 slim drive. Everuthing were fits to the box size. I tried disconnect a colling fan. But BIOS prevents starting computer without fan. After that I installed Windows 2003 Server with Windows XP drivers (video, audio and LAN). Now my mini server works good and very fast. Have a good luck.