Install model 55x or 720 memory modules

You might need to install memory modules in the server. Use the procedure in this section to perform this task.

1. Perform the prerequisite tasks described in Before you begin.
2. Stop the system. For instructions, see Stop the system or logical partition.
3. Disconnect the power source from the system by unplugging the system.
   Note: This system may be equipped with a second power supply. Before continuing with this procedure, ensure that the power source to the system has been completely disconnected.
4. Remove the system processor assembly. See Remove the model 55x or 720 system processor assembly.
5. If necessary, remove the memory modules from the system processor assembly. For instructions, see Remove model 55x or 720 memory modules.
6. Determine the slots in which the memory modules will be placed. Refer to Table 1 to ensure memory modules are balanced. Each system processor assembly has eight memory module slots. The memory modules should be plugged into the slots as shown in the following table (see Figure 1 for memory module slot locations in the system processor assembly).
   Notes:

   • When installing a quad of memory modules, all four memory modules must be the same type.
   • When two processors are installed, alternate installing memory modules between the first processor and the second processor.
   • For the models 55A and 720, memory can be installed in pairs. For the model 550, memory must be installed in quads.
   • At least one pair of memory modules is required on each installed processor card for the models 55A and 720. For the model 550, at least one quad of memory modules is required on each installed processor card.

   Table 1. Memory module balancing

   Processors and memory	Where to install memory modules
   Memory added in pairs	Plug the first pair of memory modules into memory module slots P1-C8-C1 and P1-C8-C8, or slots P1-C9-C and P1-C9-C8. Plug the second pair of memory modules into memory module slots P1-C8-C3 and P1-C8-C6, or slots P1-C9-C3 and P1-C9-C6. Plug the third pair of memory modules into memory module slots P1-C8-C2 and P1-C8-C7, or slots P1-C9-C2 and P1-C9-C7. Plug the fourth pair of memory modules into memory module slots P1-C8-C4 and P1-C8-C5, or slots P1-C9-C4 and P1-C9-C5.
   One processor, memory added in quads	Plug the first quad of memory modules into memory module slots P1-C8-C1, P1-C8-C3, P1-C8-C6, and P1-C8-C8, or slots P1-C9-C1, P1-C9-C3, P1-C9-C6, and P1-C9-C8. Plug the second quad of memory modules into memory module slots P1-C8-C2, P1-C8-C4, P1-C8-C5, and P1-C8-C7, or slots P1-C9-C2, P1-C9-C4, P1-C9-C5, and P1-C9-C7.
   Two processors, memory added in quads	Memory should be balanced on each processor card. Plug the first quad of memory modules into memory module slots P1-C8-C1, P1-C8-C3, P1-C8-C6, and P1-C8-C8 on each processor card, or slots P1-C9-C1, P1-C9-C3, P1-C9-C6, and P1-C9-C8 on each processor card. Plug the second quad of memory modules into memory module slots P1-C8-C2, P1-C8-C4, P1-C8-C5, and P1-C8-C7 on each processor card, or slots P1-C9-C2, P1-C9-C4, P1-C9-C5, and P1-C9-C7 on each processor card.

   Figure 1. Memory module slot locations in the processor assembly

   
7. Ensure that the connector is ready to receive the memory module. Remove the memory module filler, if one is present, by pushing the tabs A out and then down. The lever action of the tabs forces the memory module filler out of the connector.
   Figure 2. Removing a memory module filler

   
8. If necessary, remove the memory module from its antistatic package.
9. Ensure that the connector locking tabs A are pushed out into the unlocked position before installing a new memory module.
10. Carefully grasp the memory module B along two edges and align it with the connector.
    Attention: Memory modules are keyed to prevent a memory module from being installed incorrectly. Note the locations of the key tabs within the memory module connector before attempting to install the memory module.
11. Push the memory module B firmly into the connector until the connector locking tabs engage.
    Figure 3. Replacing a memory module

    
12. Replace the system processor assembly. For instructions, see Replace the model 55x or 720 system processor assembly.
13. Verify the installed part. For instructions, see Verify the installed part.
14. If you are installing memory modules as part of another procedure, return to the procedure now.