Asus Z170-AR Can't find boot drive on restart

torrid

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Dec 5, 2015
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I just built a system based on the Asus Z170-AR. Overall very pleased and it seems to have the features that the Z170-A lacks, such as LED indicators, power switch etc. I only have one remaining problem with the system. When I restart Windows 10 from the menu option, the system can't find the SSD boot drive. If I turn off the power supply using the switch, it finds the boot drive and starts fine.

When I am experiencing the problem and go into the BIOS I notice that the boot drive is not listed as a drive option. However, if I select the option to view all drives I can double-click on the boot drive and it restarts without a problem. I simply don't know what to try next.

To review, it's a minor problem that can easily be worked around. When restarting from the Windows 10 menu the system cannot find the boot drive. This can be fixed by 1) turning off the power supply switch and restarting the system or 2) Entering the BIOS and going into a secondary screen selecting the boot drive and restarting. Either works reliably, but neither should be necessary.

Primary System Configuration

  • MB: Asus Z170-AR (No Overclocking, latest BIOS)
    Processor: Intel Core i5-6600K
    Cooling: Cooler Master Hyper TX3
    Memory: Corsair Vengeance DDR4, 2 x 4GB, 3000Mhz (SPD Speed 2133MHz)
    PS: Corsair CX500M
    OS: Windows 10, November update
    Boot SSD: Crucial CT256 MX 100 SSD1 (Note: Not reformatted when upgrading from BIOS to EUFI. Did not reinstall Windows 10.)
    Other drives: Variety
    Case: "Legacy" Antec w/USB 2.0 front ports and Multi-card reader hooked to MB USB ports
    Video: Using MB video to support two monitors
I appreciate any ideas offered. If you need more details about the configuration, please let me know.
 
Solution
I had similar issue when I had Windows 7 on a MBR disk - When I installed Windows 10 in UEFI, it disappeared. Is your win 10 disk installed as MBR or GPT/UEFI? Have a look at UEFI / legacy boot options - They need to correspond with your installation.

Bait0000

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Dec 5, 2015
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I had similar issue when I had Windows 7 on a MBR disk - When I installed Windows 10 in UEFI, it disappeared. Is your win 10 disk installed as MBR or GPT/UEFI? Have a look at UEFI / legacy boot options - They need to correspond with your installation.
 
Solution

torrid

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Dec 5, 2015
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4,510


This may have been the problem. I know I am running an MBR drive under an UEFI. I did not have to reinstall Windows 10 when I upgraded my MB from a standard BIOS to UEFI. However, the problem seems to have "solved itself," at least I don't have it anymore. But, checking UEFI settings it is set to boot from legacy devices. So, I don't know if it "realized" after I manually pointed to the boot drive a few times to change to settings or what happened, but I suggest your reply has a high probability of being the root of my problem. Thank you.