Dell Precision 690 - Manual (Page 116)

3. Loosen the captive thumbscrews that secure the memory shroud and lift it away from the computer.
4. Disconnect the power cables from memory riser cards 1 and 2.
5. Grasp the memory riser card 1 at each corner and lift memory riser card 1 and attached card 2 from the DIMM_1 and DIMM_2 memory module connectors
on the system board.
If a card is difficult to remove, gently ease it back and forth to remove it from the connector.
6. Disconnect the power cables from memory riser cards 3 and 4.
CAUTION: Fully-buffered memory modules may become very hot during normal operation. Ensure that memory modules have had sufficient time
to cool before you touch them.
1 power connectors (4)
2 memory module connectors (4)
3 securing clips (2)
1 memory riser cards 1 and 2
2 memory riser cards 3 and 4