help find out the reason behind the server reboot.

[msmalik0101]

OS: SLES 11 SP1 x864

kernel version: 2.6.32.x

Hardware: HP 580 G7

Just before the server rebooted, following are the events logged in the /var/log/messages

May 27 03:16:35 db1 kernel: [457162.951935] mtrr: no MTRR for e8000000,4000000 found
May 27 03:16:37 db1 gdm-simple-slave[11427]: WARNING: Unable to parse output:
May 27 03:16:37 db1 gdm-simple-slave[11427]: WARNING: Unable to parse D-Bus launch output
May 27 03:16:37 db1 kernel: [457165.186590] mtrr: no MTRR for e8000000,4000000 found

Also running "cat /proc/mtrr"  returns

reg00: base=0x0c0000000 ( 3072MB), size= 1024MB, count=1: uncachable

dmesg shows:

[    0.000000] DMI 2.7 present.
[    0.000000] last_pfn = 0x83ffff max_arch_pfn = 0x400000000
[    0.000000] MTRR default type: write-back
[    0.000000] MTRR fixed ranges enabled:
[    0.000000]   00000-9FFFF write-back
[    0.000000]   A0000-BFFFF uncachable
[    0.000000]   C0000-FFFFF write-protect
[    0.000000] MTRR variable ranges enabled:
[    0.000000]   0 base 000C0000000 mask FFFC0000000 uncachable
[    0.000000]   1 disabled
[    0.000000]   2 disabled
[    0.000000]   3 disabled
[    0.000000]   4 disabled
[    0.000000]   5 disabled
[    0.000000]   6 disabled
[    0.000000]   7 disabled
[    0.000000]   8 disabled
[    0.000000]   9 disabled
[    0.000000] x86 PAT enabled: cpu 0, old 0x7040600070406, new 0x7010600070106

dmesg attached.

Please help/recommmend