do I need to do something special to use more than 4 Gigs under Feisty?

[john]

Hi all,

I just installed Edubuntu 7.04 on Server running a dual opteron, dual
core setup. The mobo is a Tyan S3992G3NR. The kernel is setup as SMP
and all cores are recognized. My problem is that only 3 Gigs of memory
is recognized. That seems odd to me, as I would expect problems (if
they occurred) to start at 4G. Does anyone know if there is something
special one has to do to enable large memory support for Ubuntu
Feisty?

The bios and MemTest86 both correctly recognize 8 Gigs.

Any ideas would be appreciated!

Thanks,

John