Troubleshooting guide

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Cisco UCS B22 Blade Server Installation and Service Note
OL-27513 -01
Removing a Blade Server Cover
Low-Voltage DIMM Considerations
The server can be ordered with low-voltage (1.35 V) DIMMs or mixed-voltage (1.35V/1.5 V) DIMMs.
There is a setting in the BIOS Setup utility that you can use to change the DDR memory mode when the
server has all low-voltage DIMMs installed. To access this setting, follow these steps:
Step 1 Enter the BIOS setup utility by pressing the F2 key when prompted during bootup.
Step 2 Select the Advanced tab.
Step 3 Select Low Voltage DDR Mode.
Step 4 In the pop-up window, select either Power Saving Mode or Performance Mode.
• Power Saving Mode–Enables low-voltage memory operation. This setting is available only if all
DIMMs installed support low-voltage operation.
• Performance Mode–Disables low-voltage memory operation. If you mix low-voltage DIMMs with
mixed-voltage DIMMs, the system defaults to this setting.
Step 5 Press F10 to save your changes and exit the setup utility, or you can exit without saving changes by
pressing Esc.
Memory Arrangement
Keep in mind the following rules when adding DIMMs to this server:
• Only use Cisco-provided DIMMs.
• Mixing different speed DIMMs causes the server to set the memory speed to that of the slowest
installed DIMMs.
• If memory mirroring is used, the total memory capacity is reduced by 50%.
• CPU1 and CPU2 (if used) must always be configured identically.