Can't get UEFI drive to boot - Chapter 2

Will do but the 860 drive can fit in only one of 2 side spot I believe. Have to run errands now. Back in 1hr

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Hopefully the manual will illustrate which are the "last two" you don't want me to use.

Try to install the new drive into the other M.2 (the one that has legacy windows)
You have 6 SATA ports. Avoid using the two on the left side.

Found this
Disabling SATA 1 if Using M.2_1??
If M.2_2 NVMe SSD is set at x4, SATA 5 & 6 are disabled. If M.2_2 NVMe SSD is set at x2, SATA 5 & 6 are NOT disabled, but the NVMe SSD has half the required bandwidth, thus lower speeds.

Try my suggestion on previous post

I tried 3 things...

1. I tried moving the SATA 1 plug to SATA 2 jack leaving SATA 1 unused. Tried that because of your post 43. No change. Booted into legacy.

2. As you suggested I moved my SATA plugs leaving the bottom 2 unused. I swapped the two M.2 drives. Booted the EFI drive and what booted was the legacy drive. So that didn't work either.

3. Knowing that the 860 drive seems to have been interfering, with the #2 setup above, I simply unplugged the 860 drive and booted. That setup booted into legacy too. I thought unplugging the 860 would work. Nope.

So no solutions yet for booting EFI and having all my drives connected. At least before I had all drives connected in EFI mode except for the 860. Maybe worth figuring out why the 860 interferes? The 860 is in the SATA jack that is the 3rd from the top. Before I moved them it was in one of the bottom 2 SATA slots you wanted me to leave unused. A clue?

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I went poking around BIOS. I don't know if these settings matter, but...

AMI NAtive NVMe Driver Support = ON
PCI Express Native = disabled
SATA mode = AHCI
Hyper M.2X16 = disabled
PCH DMI ASPM = L0s

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I just realized that in your MB picture above I already had the legacy NVMe in the bottom slot and the new NVMe in the top slot. Now they are reversed because you requested swapping them.

Can't help you anymore.
Maybe someone with a Asus MB like yours can.

Thanks for trying, mHz.

@thornev,

Can you get back to a point where both M.2 SSDs are plugged in and the computer is booting in UEFI mode from the GPT SSD? Verify you are in UEFI mode by running msinfo32 and look at the BIOS Mode line. It should say UEFI.

Navy ! Funny you should ask because that's EXACTLY where I'm at right now - booted into EFI successfully with that damn 860 SSD disconnected. That disk seems to be the issue so I'm trying to connect it to different ports to see if any of them make a difference. Nice to see you again.

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The 860 is connected to SATA port 3. Gonna try it in 6 and then 1. I'm also scouring the internet to see if anyone else has had a similar issue with that disk.

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Want to see what my disk layout is?

While you are able to boot into the GPT EFI M.2 drive, don't change anything. Reboot the computer and go into BIOS settings, look at the boot tab. See what is in Boot Option #1. I believe M1 on mine indicates M.2 slot #1. After you connect the SATA drive(s), go back into BIOS and check that again to make sure it did not change. Also, you can scroll further down that boot tab page in BIOS and see a list of devices in the Boot Override section. You can also click on the EFI M.2 SSD there to boot from it.

I'll read your post in a minute. This is interesting... 860 in SATA 6 resulted blank screen, powered itself off. I rebooted and got blank screen with blinking cursor at upper left and then PC hung. BUT...

With 860 in SATA 2 - the PC booted to legacy. Why the 2 different behaviors when the disk is in different SATA ports? The mystery unfolds. Now to read your post.

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Read your post - That BOOT page in BIOS is the one I've been editing over and over for the last 3 days. I've always been going to the Boot Override section to boot the drives.

I can tell you that the EFI drive always appears as boot option #1 whether I can boot it successfully or not. It doesn't say which M.2 port it is. It says on;y which disk it would boot. I'll see if I can capture my settings - I don't know how.

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I apologize - You're right that the M.2 port number is listed in the boot option. It says M.2_1 which is the EFI disk.

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I just tested the 860 in SATA 1 and it booted into legacy.