AN515-54-71CC not booting with 2 NVMe SSD

TinMeM

I have a NITRO 5 model AN515-54-71CC, I bought 2 XPG SX8100 512GB SSD and tried to add them to the laptop.
I want to also dual boot so I had to go into BIOS and set SATA mode to AHCI, turning this on the laptop does not boot it remains on black screen and it even does not show the Acer logo.
The coolers went on MAX rotation (at least it sounds like they are on MAX)
I waited around 10m and the screen keept black.
I had to remove all HDD in order to have access to BIOS again.
Leaving the SATA mode as RST (premium or not) the laptop boots, but since I want to dual boot I can't leave it as RST in order to install Linux.
Any ideas on how to solve this issue?

PS: Since it doesn't worked I updated BIOS to latest version (1.31 while writing this message) and the issue is still happening. 

TinMeM

Support told me that this notebook has:
1 slot PCIe Gen3x4
1 slot SATA / PCIe Gen3x2
and that the SSDs should not be compatible.

I tested them individually on both slots and they work,
I'm assuming that the controller can't handle both SSDs at the same time.
Unfortunatelly I will have to use use the second SSD on an external case, not the ideal world but at least it works.