> What memory size is supported in Scientific Linux x86_64?
> Specifically I want to install 16GB in the IBM e326 series systems and
> would like to install Scientific Linux 3.0.4 x86_64.

It shouldn't be a problem, I've got a dual Opteron system with 16G of memory running SL x86_64 4.0 and it sees it all.  I'm fairly certain that 3.0.4 will not have a problem either.  Sometimes when you don't see all of the installed memory a few bios tweaks will fix it up.

[root@master ~]$ cat /proc/meminfo
MemTotal:     16343552 kB
MemFree:      15954852 kB
Buffers:         19440 kB
Cached:         207816 kB
SwapCached:          0 kB
Active:         170316 kB
Inactive:       166140 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:     16343552 kB
LowFree:      15954852 kB
SwapTotal:     2047992 kB
SwapFree:      2047992 kB
Dirty:             360 kB
Writeback:           0 kB
Mapped:         151288 kB
Slab:            27476 kB
Committed_AS:   349896 kB
PageTables:       9848 kB
VmallocTotal: 536870911 kB
VmallocUsed:      1864 kB
VmallocChunk: 536868935 kB
HugePages_Total:     0
HugePages_Free:      0
Hugepagesize:     2048 kB


_________________________________________
Ron Jerome
Programmer/Analyst
National Research Council Canada
M-2, 1200 Montreal Road, Ottawa, Ontario K1A 0R6
Government of Canada
Phone: 613-993-5346
FAX:   613-941-1571
_________________________________________