It sees quite tricky to install ubuntu on Alienware Aurora R6 from previous posts. And right now my system is using optane, which cannot support linux... So when I change to AHCI mode, the linux installer can only see the 16 GB Optane mamory (but not 2TB HDD connect to the optane).
Right now, my plan is buy another HDD or SDD and install ubuntu on it. But it seems I still need to convert from or to AHCI and RAID if I want to use both windows and linux? Is there anyway to work out?