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Old 08-07-2013, 02:48 PM   #1
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CentOS 6.4 not recognizing all RAM?

This is a fresh install of CentOS 6.4 x86_64 - Minimal with Development Tools installed and wget installed. So far nothing else has been installed. The machine has 8gigs of RAM installed but

free -m

             total       used       free     shared    buffers     cached
Mem:          3137        188       2948          0          6         82
-/+ buffers/cache:         99       3038
Swap:         3279          0       3279
Why does it only see half of the installed RAM? I've checked the box and it's all seated solidly. Is there a motherboard limitation here? Something else I can do to force it to see the rest? Thanks for any help, and if I need to provide any more info just let me know!

BIOS reports
Memory Installed              6144MB
Memory Available             6143MB
Memory Speed                  800MHz
Memory Channel Mode     Dual
Memory Technology         DDR2 SDRAM
dmesg | head -n 25

Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Linux version 2.6.32-358.14.1.el6.x86_64 ( (gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) ) #1 SMP Tue Jul 16 23:51:20 UTC 2013
Command line: ro root=/dev/mapper/vg_fms-lv_root rd_NO_LUKS LANG=en_US.UTF-8 rd_LVM_LV=vg_fms/lv_swap rd_MD_UUID=f92a45ba:0b40b12f:78972b39:f598db0e rd_LVM_LV=vg_fms/lv_root SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_MD_UUID=f5fafd99:42d14092:ea0204a7:4b95b16a  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet
KERNEL supported cpus:
  Intel GenuineIntel
  AMD AuthenticAMD
  Centaur CentaurHauls
BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 0000000000099c00 (usable)
 BIOS-e820: 0000000000099c00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 00000000cfe90000 (usable)
 BIOS-e820: 00000000cfe90000 - 00000000cfee3000 (ACPI NVS)
 BIOS-e820: 00000000cfee3000 - 00000000cfef0000 (ACPI data)
 BIOS-e820: 00000000cfef0000 - 00000000cff00000 (reserved)
 BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
 BIOS-e820: 00000000fec00000 - 0000000100000000 (reserved)
DMI 2.5 present.
SMBIOS version 2.5 @ 0xF0BE0
DMI: Dell Inc. Vostro 400/0GN723, BIOS 1.0.11 01/31/2008
e820 update range: 0000000000000000 - 0000000000001000 (usable) ==> (reserved)
e820 remove range: 00000000000a0000 - 0000000000100000 (usable)
last_pfn = 0xcfe90 max_arch_pfn = 0x400000000
MTRR default type: uncachable

Last edited by dzedward; 08-07-2013 at 03:22 PM. Reason: added bios info
Old 08-07-2013, 03:51 PM   #2
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If your BIOS is not reading it than Linux isnt even apart of the equation. Try swapping sticks and see if you can find one that is bad. Working on a 20,000 sq ft datacenter I can tell you it is very common for RAM to be DOA, I replaced at least 1-2 a week.
Old 08-07-2013, 05:05 PM   #3
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Thanks Kustom42! I think you're right and one of the sticks is DOA. I flashed an updated BIOS and it's realizing 6gb now, so yea, I think one of them is just dead. Thanks again!

I don't know how to mark this as answered
Old 08-07-2013, 05:05 PM   #4
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Top right corner of the first post on the thread there is a "Thread Tools" drop down to mark something as solved.


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