950 Pro 512 GB SSD as MBR, Windows 10 won't install unless GPT

[edvalens]

I am trying to install Windows 10 on a new build (ASUS Z170-Deluxe). The SSD is a Samsung 950 Pro 512GB and is the only drive installed. Windows 10 is on a DVD. I get past the product key, the license, to the where do you want to install the OS? The only disk is my SSD. But it says "The selected disk has an MBR partition Table. On EFI systems, Windows can only be installed on GPT disks." So do I somehow convert my SSD to GPT (how?) or change something in the BIOS to allow the SSD to be recognized as GPT or at least non-MBR. The ASUS rep suggested connecting a normal HDD, loading the OS on that, then reformatting (to GPT) the SSD, then reloading the OS to the SSD. sounds like a pain. is there an easier way? oh my SSD is an M.2 form factor installed in the M.2 slot on the mobo.

 

[The Original Ralph]

You'll have to re-install your original OS drive, with the 950 PRO installed as well, go to disk management - on the left hand side of the table, to the left of the white box showing the 950, in the grey box listing it "Disk "0" or "1", and it will say basic, right clik in that grey box and in the sub-menu that opens, you should see a selection "convert to GPT"

then you'll have to format it NTFS and you're set

 

[edvalens]

there is no original OS drive - this is a new system with only the 950 Pro installed. Maybe some changes in the UEFI BIOS would make the SSD as first seen GPT rather than MBR. There must be some legacy settings.

 

[The Original Ralph]

if you have another computer you can install it in otherwise RUFUS, which is what a lot of folks have used to install windows on these drives, i believe will partition your drive GPT

http://rufus.akeo.ie/

 

[edvalens]

I tried installing the OS from a bootable USB drive by using RUFUS to create a bootable USB ISO file by going from the Windows 10 DVD to an image then to the ISO. But after the "Setup is starting" the message "Windows setup could not install one or more boot-critical drivers - to install windows make sure the drivers are valid and restart the installation". So I got further with the installation by using the DVD directly. I'm not sure what drivers it is looking for. My other computer (2007 era) won't install a M.2 drive.

 

[The Original Ralph]

it might be looking for the samsung NVMe driver they released for the 950 PRO - scroll down a bit and you'll see it

http://www.samsung.com/global/business/semiconductor/minisite/SSD/global/html/support/downloads.html?CID=AFL-hq-mul-0813-11000170

 

[JohnnyLucky]

Did you do anything to the 950 Pro before the installation attempt?

 

[edvalens]

No - but I think what happened was because I copied the DVD (Win10) image on my old computer and created the ISO on my old BIOS-type computer, when I clicked "New" on the Win10 installation, it created the MBR partition in the virgin SSD. This could also have been because of CSM (compatibility mode) or other boot options on the new computer which are legacy (BIOS) related. Anyway, the installation from the USB failed (because some USB 3.0 drivers weren't on the ISO), but the partition remained. So when I next tried the direct DVD installation, (the "New" option was no longer available) which should have gone to GPT, it failed also because the new computer is a UEFI computer which has to be an OS with GPT. So it's like the SSD was contaminated with the MBR from the old BIOS setup. I think the only solution is to wipe it clean and retry the installation as "New". But that means having a working system that will recognize the SSD and allow me to reformat it.

 

[The Original Ralph]

here are the instructions posted on the asus mobo support forum by one of the mods for cleaning the new SSD before using RUFUS -

Start by checking that you see the SSD in DiskPart:
Press <Shift-F10> to enter Command Prompt when Windows installation stops for selection of language.

If you feel uncomfortable here, remove data cables from all other drives.

Type:
diskpart <Enter>
DISKPART> list disk (list all drives)
DISKPART> select disk 0 (in this example the target SSD is disk 0)
DISKPART> clean (option for cleaning the selected drive disk from any previous data)
DISKPART> list partition (option for listing the partitions on the selected drive)
DISKPART> exit (exit from DiskPart)
exit (exit from Command Prompt)

Do you see the SSD here?

If you are using a USB stick as installation media, create it with Rufus, Just copying the information from the Win 7 DVD does not work!
Choose FAT32 formatting.
Choose GPT partition scheme.
You need an ISO file of Windows 7 SP1.DVD does not work Choose FAT32 formatting.
Choose GPT partition scheme.


or you might post asking in the asus mobo forum - link is to the 3rd page of the forum, first 2.5 pages are "stickies"

https://vip.asus.com/forum/topic.aspx?elitepost=0&SLanguage=en-us&board_id=1&page_size=20&page=3&count=193900

 

[edvalens]

Fixed the problem - first recreated a bootable USB ISO file using MS Media Creation tool (which also downloaded Windows 10). Then went into UEFI, made USB which it recognized as "UEFI Sandisk" USB stick as the top boot priority, changed Secure Boot to "Other OS", CSM-enabled and Legacy OProm, Legacy Only, Legacy Only and UEFI Driver first. Then saved and exited UEFI. On rebooting, Windows 10 started to load and when got to "where do you want to install?", the two MBR partitions showed up. It wouldn't allow me to format, but would allow Deletion. So deleted both the old partitions, Then had "Drive D-unallocated space" of 476.9 GB. Pressed "New", Apply and OK. Windows created 4 partitions, the last was Drive 0, Partition 4, 476.4GB Primary. Highlighted that one and clicked on Next. Installed Windows 10 in about 10 minutes. So I am now good to go. Loaded ASUS Drivers and Utilities and Samsung NVMe driver and am now in business. Thanks to everyone that provided help.

I think the original problem of MBR was caused by not reading the fine print in RUFUS - it created MBR partitions by default which then carried over to the SSD. I should have selected GPT partitions for UEFI when I tried to create the bootable USB stick.