RAM not showing up in ubuntu 64 bit server :S

[virumaandi]

I am using a physical machine for server ( 343's server files )
Configs are
Core2Duo E 4400 2.Ghz (EM64T capable)
4x2GB DDR2 667 Mhz RAM in Dual Channel
in my BIOS it shows total RAM as 8096 MB
and i Did download Ubuntu server 10.04.3 64 Bit for AMD 64 platform(which has support for xeon core2Duos and core2Quads etc)
and installed it .
when i type in terminal " free -m " to check the ram it shows as 3261 GB

and for cpu info when i typed this

 #grep flags /proc/cpuinfo " 

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge  mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm

also this command clearly verifies that my CPU suuports PAE
"
grep --color=always -i PAE /proc/cpuinfo"

CPU Modes:( Source Ubuntu Forums )

• lm flag means Long mode cpu - 64 bit CPU
• Real mode 16 bit CPU
• Protected Mode is 32-bit CPU

so Clearly my system is 64 bit capable just not sure why am having this problem . and I tried Ubuntu 11.04 64 bit server .
I still couldnt fix my problem
i have 4 x 2 GB ram modules but only 3.2 GB is shown with

#free -m
              total       Used      Free    shared     buffers
Mem:           3261       1462       1798        0          87

BIOS detects full 8 GB and with

#dmidecode | grep Size | Grep MB
Size : 2048 MB
Size : 2048 MB
Size : 2048 MB
Size : 2048 MB

I tried for a solution everywhere and was in ubuntu forums for over 2 days still cant find any answer . Please help am ready to give any info needed

[MentaL]

[loko9988]

install kernel with BigMEM option.....

apt-cache search bigmem

[virumaandi]

install kernel with BigMEM option.....

apt-cache search bigmem

#apt-cache search bigmem

i got nothing no errors or it showed up anything . Man am kinda newb with linux a little direction will help

[das7002]

Run memtest86, one of your RAM sticks might be faulty as 64 bit doesn't need anything special to see past 4gb of ram...

[virumaandi]

Run memtest86, one of your RAM sticks might be faulty as 64 bit doesn't need anything special to see past 4gb of ram...

Firstly Thank you both for replying :D and das i tried memtest for complete address range i got no errors

[MentaL]

32bit runs only 4gb.

[virumaandi]

32bit runs only 4gb.

yea but my version is Ubuntu 11.04 64 Bit server edition am double sure about that . thats the only thing am stuck at. everything else is working fine for me :(