Question How to upgrade from one m.2 boot drive to another on Asus z370 f gaming mobo?!

Feb 14, 2019
Hi all,

I'm really hoping someone will see this and know how to help!

I built my first PC about 2 years ago with a 250GB 860 EVO m.2 installed as my boot drive in the lower m.2 slot in the Asus z370 F gaming motherboard. This is the only m.2 slot I have available to me as the other one (top slot) is PCIE only (or something - still not quite sure why it won't work :)

I am running out of space in the 250GB drive so I recently bought a new 1TB 970 EVO as a replacement. I used Macrium Reflect to clone my boot drive to a 500GB external drive, which seemed to go very smoothly. I removed my old 250GB boot drive, installed my 1TB new drive in the same slot, and tried booting off my external drive, but I can't get it to boot up.

I have changed the boot priority in my BIOS to the external drive and have tried disabling "secure boot" in my BIOS to be able to boot from the external drive, but it still won't boot up. Does anyone know of step-by-step instructions for how to get this to work? I have watched countless Youtube videos and read numerous posts, but everything I try just doesn't seem to work.

For now, I have reinstalled my 250GB boot drive and everything is back to normal. I'd really like to be able to boot from my 1TB drive though! Any help or suggestions would be VERY MUCH appreciated!

Thanks in advance!
Hi drmcbeefy :)

If Macrium reflect successfully cloned your drive then why are you trying to boot from an external drive?
I would select the new drive as priority in Bios and leave the old drive out of the loop for now. If the cloning was indeed successful then you should have no issues.

As I don't know what type of partition was on the old drive If you do have issues then you probably have a cloned drive with the wrong partition table active. When cloning you have a choice of GPT and MBR. GPT is used when booting UEFI and is a selection in Bios.

Go here to better understand:
and here:
Feb 14, 2019
Thanks MeanMachine41!

I was trying to clone my boot drive to my external drive and then install my new 1TB m.2 drive as my new boot drive. Once booted off the external drive, I was going to put the boot drive back onto my new 1TB drive to make that my new boot drive. Unfortunately, I only have one functional m.2 drive to work with. Ultimately, I just want to transition my boot drive from my old 250GB m.2 to a new 1TB m.2, but have to do so with only one m.2 slot on my mobo. Is there a better way to do this than using an external drive?
Your 970 m.2 is a pcie drive which I think you can install in your top m.2 slot.
Then download and install the Samsung pcie nvme drivers from the Samsung web site.
Then you should be able to use the Samsung ssd migration app to move your c drive to the 970 drive.
Change the boot order and you are done.

This is the procedure I used with no issue.

For security reasons, I do not think windows can boot from an external drive without going through a bunch of hoops.

On your motherboard, read the manual carefully.
M.2_1 shares the sata 1 port.
M.2_2 shares the 56 sata ports when pcie mode which is what you want for a 970 device.
Feb 14, 2019
Thanks Geofelt!

I did exactly what you described and IT WORKED!!!! Thank you so much!! It is now showing my 1TB m.2 as the boot drive (C:) and my old 250GB m.2 as an additional drive (F:)!

Just one more newbie question: If I want to free up the old 250gb m.2 drive for games, files, etc. and reformat it to clear it, will my current games/applications/etc be able to find the new cloned file extensions on the new cloned 1TB boot drive?

I'm not sure if I know how to ask the question correctly -- If I start up a game or other application after I've reformatted the old 250gb m.2 drive, will those applications be able to find the info they need to start up from the cloned 1TB drive? Or will they be searching for them on the old 250gb m.2 drive that has now been reformatted? Does that even make sense?

Thanks again!
When you used the Samsung app, you moved the C drive and all of it's contents to the 1tb m.2 drive.
That will include a couple of hidden partitions that were on the old drive.
You can do what you will with the old 240gb drive.
Prove it to yourself by booting with the old drive disconnected and you should have access to everything.
Essentially, you will have deleted the old drive from your system.

If you reconnect it you can use windows storage management to reformat the 240gb drive as a normal data drive.
Just be certain that you pick the 240gb f drive to reformat and not your new os drive!

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