Users Guide

14 Information Update
Processor Upgrades
If you add one or more processors to your system, ensure that all processors have the same stepping value
and the same cache size and technology. If you install processors with different speeds, they will operate
at the speed of the slowest processor.
You must install all voltage regulator modules (VRMs) included in the upgrade kit in addition to the
processors. See "Processors" in your Installation and Troubleshooting Guide for details on installing
processors and VRMs.
Memory Test at System Startup
The System Memory Testing option in the System Setup program is disabled by default. If the option is
enabled, the system memory is tested at each system startup. Systems with large memory configurations
may take more time to complete the memory test. See your User’s Guide for information on the System
Setup program.
Linux Operating System Information
Booting Red Hat Enterprise Linux AS (Version 4) for Intel x86 With More than Eight Logical
Processors
A system running the Red Hat Enterprise Linux AS (version 4) for Intel x86 operating system will fail
to boot if it is configured with more than eight logical processors. To work around this issue, pass the
parameter apic=bigsmp to the kernel command line at system boot. A correction for this issue will
be available in a future Red Hat Enterprise Linux Version 4 Update.
Using More than Eight Logical Processors With Red Hat Enterprise Linux (Version 4)
for Intel EM64T
A limitation in the Red Hat Enterprise Linux (version 4) for Intel EM64T operating system will cause the
operating system to use no more than eight logical processors even if more processors are present in your
system. On systems with more than eight logical processors, the Linux operating system will recognize and
report only eight processors. For more information about this limitation, see the
Red Hat Enterprise Linux 4
Update 3 Release Notes
on the Red Hat web site at http://www.redhat.com/docs/manuals/enterprise/ .
Rebooting Red Hat Enterprise Linux AS (Version 4) for Intel EM64T
The system may hang when the message Restarting System appears while rebooting a system
running the Red Hat Enterprise Linux AS (version 4) for Intel EM64T operating system. If this occurs,
use the power button to power off the system. A correction for this issue will be available in a future
Red Hat Enterprise Linux Version 4 Update.