RAM not correctly detected after install

Please show the output of:

lsblk -o NAME,FSTYPE,MOUNTPOINT
sudo fdisk -l
➜ lsblk -o NAME,FSTYPE,MOUNTPOINT
NAME        FSTYPE MOUNTPOINT
nvme0n1            
├─nvme0n1p1 vfat   /boot/efi
├─nvme0n1p2        
├─nvme0n1p3 ntfs   
├─nvme0n1p4 ntfs   
├─nvme0n1p5 ntfs   
├─nvme0n1p6 ext4   /
└─nvme0n1p7 ext4   /home
➜ sudo fdisk -l                                      
Disk /dev/nvme0n1: 476.94 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: KINGSTON RBUSNS8154P3512GJ1             
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: D78898B2-5384-421B-8E85-DDC70656FF83

Device             Start        End   Sectors   Size Type
/dev/nvme0n1p1      2048     206847    204800   100M EFI System
/dev/nvme0n1p2    206848     239615     32768    16M Microsoft reserved
/dev/nvme0n1p3    239616  376293375 376053760 179.3G Microsoft basic data
/dev/nvme0n1p4 376293376  499173375 122880000  58.6G Microsoft basic data
/dev/nvme0n1p5 499175424  501272575   2097152     1G Windows recovery environment
/dev/nvme0n1p6 501272576  668184575 166912000  79.6G Linux filesystem
/dev/nvme0n1p7 668184576 1000214527 332029952 158.3G Linux filesystem

Yes, but while I am able to understand the path of EndeavourOS

Boot0002* EndeavourOS   HD(1,GPT,b56d0599-5279-4e30-b3ba-f104ed33ce9e,0x800,0x32000)/File(\EFI\EndeavourOS\grubx64.efi)

I am not able to understand the path of those entries I cannot get rid of, eg:

Boot0003* deepinfromubi.efi     PciRoot(0x0)/Pci(0x14,0x0)/USB(12,0)/HD(1,MBR,0x179de,0x3f,0x777ff5d)/File(\EFI\BOOT\fromub.efi)A01 ..

Can you explain what’s with the first part (before HD): PciRoot(0x0)/Pci(0x14,0x0)/USB(12,0)/... ? I am confused at this part.

You clearly don’t have the disks that those additional entries are referring.
Looks like you had some USB drive attached when those entries were created.

There was something about boot-repair, and maybe that is related to the confusion?

Indeed. So they cannot be removed unless I insert that USB drive?

The boot-repair is not linked with those entries I think. In a previous post I’ve shown indeed that I have a boot-repair directory in boot/efi but at this moment it’s gone as I have removed it in the meantime (just to clean a bit /boot/efi partition).

No, this is not what I meant.

Even though I’m not familiar with the internals of boot-repair, I have a hunch that your additional entries are simply leftovers of it (or maybe a similar tool), possibly in some related configuration file of boot-repair.

So I suggest you search more info about boot-repair and what it does exactly (or another similar tool if that was used).

Maybe someone else here is familiar with boot-repair and can help more?