8 gb of RAM installed but only 4 gb is showing up?
 

Ok, I've searched high and low and am almost at my wits end with this one. I recently upgraded from Mandriva 2010.2 to OpenMandriva Lx (which I should've done a long time ago). Quick specs: I've got an ASUS M4A78T-E mobo, 2 sticks 4 Gb G.Skill DDR3 Sdram, BIOS recognizes both of them just fine, OpenMandriva Lx has the 3.15.10 kernel, running KDE 4.13.3, after everything was set up I added a SuperKaramba system monitor to the desktop, then I noticed it was only showing little less than 4 Gb RAM. Here is the output of cat /proc/meminfo:

MemTotal: 3368412 kB
MemFree: 299388 kB
MemAvailable: 1297228 kB
Buffers: 106896 kB
Cached: 1072132 kB
SwapCached: 0 kB
Active: 1957976 kB
Inactive: 926860 kB
Active(anon): 1388036 kB
Inactive(anon): 359172 kB
Active(file): 569940 kB
Inactive(file): 567688 kB
Unevictable: 0 kB
Mlocked: 0 kB
HighTotal: 2566728 kB
HighFree: 148192 kB
LowTotal: 801684 kB
LowFree: 151196 kB
SwapTotal: 2978708 kB
SwapFree: 2978668 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 1705880 kB
Mapped: 345208 kB
Shmem: 41352 kB
Slab: 83796 kB
SReclaimable: 49384 kB
SUnreclaim: 34412 kB
KernelStack: 7408 kB
PageTables: 8388 kB
KsmZeroPages: 102344 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 4662912 kB
Committed_AS: 4546620 kB
VmallocTotal: 188416 kB
VmallocUsed: 28588 kB
VmallocChunk: 139876 kB
HardwareCorrupted: 0 kB
AnonHugePages: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 4096 kB
DirectMap4k: 45048 kB
DirectMap4M: 794624 kB

Here is the output of dmidecode -t 17:

SMBIOS 2.5 present.

Handle 0x0036, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0034
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM0
Bank Locator: BANK0
Type: Unknown
Type Detail: None
Speed: Unknown
Manufacturer: Manufacturer00
Serial Number: SerNum00
Asset Tag: AssetTagNum0
Part Number: ModulePartNumber00

Handle 0x0038, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0034
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: DIMM1
Bank Locator: BANK1
Type: DDR
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Manufacturer01
Serial Number: SerNum01
Asset Tag: AssetTagNum1
Part Number: ModulePartNumber01

Handle 0x003A, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0034
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM2
Bank Locator: BANK2
Type: Unknown
Type Detail: None
Speed: Unknown
Manufacturer: Manufacturer02
Serial Number: SerNum02
Asset Tag: AssetTagNum2
Part Number: ModulePartNumber02

Handle 0x003C, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0034
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: DIMM3
Bank Locator: BANK3
Type: DDR
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Manufacturer03
Serial Number: SerNum03
Asset Tag: AssetTagNum3
Part Number: ModulePartNumber03


Here's free -m:

total used free shared buffers cached
Mem: 3289 3057 231 0 95 1059
-/+ buffers/cache: 1901 1387
Swap: 2908 0 2908

I've tried them on banks 0 & 2, then on 1 & 3, nothing changes.

Anyone have any clue what's going on here?

32 bit operating systems can only see 4 gig of ram

so i am guessing you downloaded and installed the 32 bit OpenMandriva
i am guessing this one
http://sourceforge.net/projects/open...elease/2014.2/
the i586
OpenMandrivaLx-2014.2.i586.iso

use the x86_64 64 bit version

Actually, my Mandriva 2010.2 was a 32 bit OS and it "saw" 8 Gb of RAM just fine.

Physical Address Extension (PAE) allows a 32Bit OS to address more then 4GB of memory. As far as I know PAE is enabled by default for X86 kernels these days.

Look at the output of the command:
cat /boot/config-$(uname -r) | grep PAE

If the output looks like the following then PAE is enabled and something else is the problem.
CONFIG_X86_PAE=y

Can run memtest too but see what it says you have. Run the test too but see what it reports exactly.

The board should support up to 16G.
I'd think that generally you'd have to find a non-pae version but that could be checked for sure. As the pae is common (edit)

There are three options in kernel config for 32-bit kernel memory usage.

CONFIG_NOHIGHMEM
CONFIG_HIGHMEM4G
CONFIG_HIGHMEM64G

Our OP has obviously second option enabled.

It appears John VV got it right. I installed the x86_64 distro and it now recognizes my RAM. Thanks John!

Odd, I'd have thought that the 32 bit version you had supported pae by default.

Oh, well, 64 bit should be OK. Thanks for the update and solution.

Older CPUs do not support PAE, PAE-enabled kernels will not boot on those. Distro maintainers probably wanted to keep supporting those old CPUs with their 32-bit version.

Pretty sure his board is a 64 bit board and could easily run pae.