Boot drive suddenly goes missing and machine starts in BIOS

There is no Boot file on the 2TB SSD. If there was, when you boot the computer with the drive inserted or even using a USB Adapter,. Windows would assign a drive letter.

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If you mean the .efi file, that should be on the esp partition. Windows won't automatically assign a letter to the esp partition

In a default windows installation there are two .efi files . Both are on the esp partition.

SIW2 said:

It needs a drive letter to see it in explorer




The word Boot only shows in diskmgmt for the partition you are currently booted into. You wouldn't expect to see it on a different disk.

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Thanks for that info.
I assigned D: to the drive in Disk Management and I was able to see the Windows install on it.

I put it back in the machine m.2 slot and It still was not recognized by the motherboard. (which recognizes the Crucial drive) Not listed in the BIOS

I then I plugged it into the computer using via USB using the external enclosure and it show up in the BIOS. However, when I tried to boot from it in the enclosure, Windows said it need to be repaired. That eventually lead to a windows "Reset".

After the windows reinstall, the machine started with the OS ssd still in the external enclosure.

In the morning I'll try swapping back to the motherboard m.2 slot. Hope it works.

Ok, So as I said, the machine started from the drive in a an enclosure. However, putting it back in the mobo m.2 slot and it was not recognized. I then tried a couple other drives. newer Silicon Power 2TB, and an old 256GB. Both were not recognized and did not show up in the BIOS. Only the Crucial consistently does. I'll test with one more drive tomorrow, but I'm dreading that this is a MOBO problem and I have to return or RMA it?

CalypsoArt said:

Ok, So as I said, the machine started from the drive in a an enclosure. However, putting it back in the mobo m.2 slot and it was not recognized. I then tried a couple other drives. newer Silicon Power 2TB, and an old 256GB. Both were not recognized and did not show up in the BIOS. Only the Crucial consistently does. I'll test with one more drive tomorrow, but I'm dreading that this is a MOBO problem and I have to return or RMA it?

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As I mentioned above this really sounds like it's not a Drive issue but a problem with the way these mini ITX motherboards connect the main M.2 slot together. You have to ensure all the contacts are meshed together. Not simply the M.2 socket with the NVMe drive but the other parts. Again however not sure about this specific motherboard.

BamaInArk said:

You have to ensure all the contacts are meshed together. Not simply the M.2 socket with the NVMe drive but the other parts.

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I'm not sure what you mean? Are you referring to other components? I just can't explain why it originally worked, and now, of four drives tried in that slot, one drive is consistently found but the others are not. Also the second drive in the second slot is always found. Still, I find it hard to believe everything worked, and it suddenly went awry so soon.

Do you have any other disk management programs?
I use Disk Genius... DiskGenius: Data Recovery, Partition Manager, Backup & Disk Utilities

PenPusher said:

Do you have any other disk management programs?
I use Disk Genius... DiskGenius: Data Recovery, Partition Manager, Backup & Disk Utilities

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I do not though I have used Partition Manager in the past.

So the latest in this saga.

I got a new PREDATOR 2TB drive. I installed it. The BIOS found it. Great! I then restarted to install Windows, chose the drive. The install began, and then quickly restarted, and now the drive is no longer visible in the BIOS. I then cleared the CMOS, restored the BIOS to the previous version, started the computer and the BIOS shows both SSD drives. Yay! I begin Windows install, and the machine restarts at some point -- I'm not sure if it was a Windows install required start of some sort of hang -- anyway on the restart it goes back into the BIOS and the drive is again missing.

I repeated this three times by updating to the latest BIOS, rolling it back, then updating it again. Each time the BIOS was installed is displayed both drives, and each time I tried to install Windows the drive again disappeared during the process. This happened with three different drives two of which are brand new and work when tested in USB enclosures. At any rate, I've initiated a Mobo exchange with Amazon and the new board arrives tonight. I don't know what I'll do if the problem repeats?

Do you have any Bios screen shots of the problem?
Have a fat 32 formatted usb stick in a usb 2.0 port and press f12 to capture...

PenPusher said:

Do you have any Bios screen shots of the problem?
Have a fat 32 formatted usb stick in a usb 2.0 port and press f12 to capture...

View attachment 130350

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Thanks for the response. I have this image but I've already initiated the motherboard return and the replacement just arrived. We'll see if the problem resurfaces with the new mobi.
This is what was happening and displayed in the BIOS. The first red circle is where the OS drive should be and is not, the second where the boot drive/manager should be. It all worked at one point.

OK. So I re-assembled the machine with the new MOBO. Both SSDs show up in the BIOS. Current Version is 0825 11/29/24. There are 3 versions since then. The latest is Version 1022 dated 03/07/2025. Should I update? Here is what the ASUS site says.

Version 1022.
1. Enhanced system performance with support for 9950X3D and 9900X3D processors.
2. Included AI Cache Boost to enhance performance and compute power when using AI-based tools.
Before running the USB BIOS Flashback tool, please rename the BIOS file (A5621.CAP) using BIOSRenamer.

I'm worried that the BIOS update is what brought about the problem.

If it's all working ok now and your happy with it, I would not update the Bios unless you have a problem related to a specific area.

So I did update the BIOS on this replacement motherboard to the second most recent. (The one it shipped with was the first after the Beta)

All is working fine. All drives found, windows and a couple applications installed. I think I'll hold off completely transitioning to this machine for a while since I'm still nervous. The previous build also worked well before it began not seeing the OS drive. Anyway, thanks to all who helped. Hopefully I won't be needing you guys for this particular problem again.