FreeBSD-amd64-RC1 problem on Dual AMD64 with 8GB RAM (IBM @server 325, ServeRAID 6M)

[Ganbold]

Hi,

Now FreeBSD is started not working again even with 4GB of RAM. I added 4GB 
of RAM before and with total 8GB of RAM
some tools and programs are started not working. Then I reduces RAM back to 
4GB and still same things are
happening. Now I can't even login. Login exits with error.
Somehow added RAM caused break in entire system.

Any idea what is wrong with this? When FreeBSD-AMD64 will support more than 
4GB of RAM?
Should I install FreeBSD again? Or is there anyway I can fix?

thanks in advance,

Ganbold