When the OP is saying switching it manually I don’t think he means physically? Or is changing it from the boot order in Bios? 
I think he does 
Maybe? 
Edit: Why would you need to?
Edit2: The OP said both were internal so I question that.
My problem is … after some hours trying to install nvidia card (+prime) on EOS (AND I MADE IT once again thank you @ricklinux and @manuel hehe) Iimagine I want to use ubuntu for some reason. As soon I remove EOS ssd I will be only abe to return to EOS if i use
Manjaro installation media (pendrive) and pick the Detect UEFI Booloaders option. After that i get the EOS grub menu I need to to this everytime i want to boot with EOS ssd.
When the OP is saying switching it manually I don’t think he means physically? Or is changing it from the boot order in Bios
physically. Yes … 2 ssd’s which i change them physically. My laptop has only one 2.5’’ bay. Cant have more than 2 ssd’s.
Bad idea! 
I put my 
in 
that he swaps them physically.
That doesn’t mean that each is not used internally.
Oh …okay it’s a laptop. 
Edit: I’m so confused. 
Bad idea!
LOLOL Even if I want … I couldnt lol almost extreme temperatures with Ubuntu 
Btw I just need the files inside the ssd 
Okay so here’s my theory. When you pull out a drive and change it for another you most likely need to enter the Bios and select the drive it’s booting on. It may be because Ubuntu is installed in Bios mode. The only way to confirm that is if you boot on the Ubuntu drive and see if it’s in Bios mode or not.
Edit: Better idea is to never use ubuntu again or install it on the same drive and dual boot. I’m assuming you can’t put both drives into the laptop as it doesn’t have the bay for it. 
If you just want the files off of it then you should be able to copy them to a usb. Then when you boot back on the EOS drive you can copy them then.
I can’t see myself doing that. I mean putting my hands in the fire!
If you have or you could get one, use a ssd-usb adapter, connect your Ubuntu drive externally.
If your Ubuntu is installed in UEFI mode as well, you could then use EnOS’ Grub to boot it. No need to swap them again.
That’s the talking of people in doubt 
If you have firm convictions then you know … you can walk through fire! 
@sysope
My suggestion is to get one of these Orico external 2.5 sata drive usb enclosure and then you can plug the drive into a usb port and get your files off and then after format the drive and you have a portable usb drive. They are cheap @ $9.99 Cdn.
Edit:
Also as @pebcak said if Ubuntu is in UEFI mode which i now assume it is maybe since i didn’t realize you were physically swapping the drives. You could use it as he stated.
It comes with the cable also.
Could it be that Ubuntu is using Secure Boot?
EndeavourOS does not support it.
Also the idea from @ricklinux (BIOS legacy boot vs. UEFI boot) is worth checking.
You could show the output of commands
lsblk -fm
sudo fdisk -l
on both EOS and Ubuntu disks.
Edit: Better idea is to never use ubuntu again or install it on the same drive and dual boot. I’m assuming you can’t put both drives into the laptop as it doesn’t have the bay for it.
I will never use ubuntu or any distro again lol Im cool with EOS
And yes, theres only 1 bay for the ssd.
The real reason is this …
If u recall …
ricklinux Said:
It has the right drivers installed for the Nvidia card but is booting and running on Intel. You would have to use optimus manager or some other option to switch if you want to run on the nvidia graphics.
I did Thanks to you 
But now my laptop is reaching 70º celsius (temperature room 28º).
Edit: If you don’t have any need and you’re satisfied you can just continue running on the Intel gpu.
Since laptop is getting higher temperatures BUT everything works (even if my hands burn from the 70º lol) I would not mind to install EOS on the other ssd without nvidia just to check if I get lower temps. ALL … on the condition that after I swap ssd’s everything works fine with the original EOS (the one with nvidia installed the one with high temp)
I have a firm conviction that if i stick my hands in the fire I’m going to get burned!
1 Like
Then you most certainly will 
1 Like
That’s too hot! Not sure why that would be happening.
1 Like