Only 2.7 GB RAM detected out of 4+ GB in Bios & MainBoard

[Husse]

This is a very confusing post
The subject line is

Only 2.7 GB RAM detected out of 4+ GB in Bios & MainBoard

Well if that's the case it's time for you to return the board to the seller and demand one that is not faulty
Then you say

I couldn't find any 'bigmem' precompiled kernel on the regular repositories.

You claim to have Felicia 64 bit......
The somewhat ominous message
'Aperture beyond 4 Gb, Ignoring
is there on my system with 2 GB as well, and my 64 bit Felicia works quite well - I think we can ignore it