FreeBSD 6.0, amd64, A8N-SLI and 4gb ram

[Robert Leftwich]

I've been running FreeBSD 6.0 stable on an A8N-SLI Premium amd64 box
with 2gb of ram for a few weeks now and it has been running well, but
some of the analysis I run needs more ram, so I dropped in another 2 gb
and started having all sorts of weird problems, such as DHCP failure and
running very slowly. I tracked it down to 2 bios settings, both related
to PAE (one turning on s/w PAE, the other h/w) - if i turn both of those
off, then everything works, but FreeBSD can only see 3gb of ram. Some
documentation suggested a custom kernel with 'options PAE'  enabled
would be required, but adding that generates an 'invalid option PEA'
error when running make. Is it possible for FreeBSD to access the full
4gb on this m/b?

Robert