The information in this site is the result of my researches in the Internet and of my experiences. This information below is solely used for my purpose and may not be suitable for others.
New Partition Scheme:
My new system, Dell Precision 3640 Tower, uses UEFI and its partion (/dev/sda2) needs to be formatted as vfat. Detail can be found at Gentoo Wiki: EFI System Partition
|/dev/sda1||2MiB||-||BIOS boot partition|
|/dev/sda2||128MiB||vfat||UEFI boot partition|