Dell Vostro 260 (Mid 2011) - Manual (Page 38)

NOTE: The processor is notched at one end with a triangle marking. The same
marking is also notched on the processor socket.
2. Press down on the release lever to lock it with the retention hook.
3. Close the processor cover.
4. Place the heat sink and fan assembly on the processor.
5. Tighten the captive screws securing the heat sink and fan assembly to the
system board.
6. Connect the heat sink and fan assembly cable to the system board.
7. Replace the
cover .
8. Follow the procedures in After Working Inside Your Computer .
38