my %lookup_row;
foreach my $row ( @RAM ) {
    my $hash = hash($row);
    if ( defined $lookup_row{$hash} ) {
        push @{ $lookup_row{$hash} }, $row;
    }
    else {
        $lookup_row{ hash($row) } =  [$row];
    }
}

foreach my $row ( @RAM2 ) {
   if ( exists $lookup_row{ hash($row) } ) {
      # potential match
      # check for collision
   }
}

sub hash {
    # something that makes sense for your data
    # probably join in this case. 
}