NVMe boot drive and BIOS numbering

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scolla66

scolla66

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Jul 31, 2012
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So, I took the plunge and bought an NVMe M.2 drive for Windows. Install went great and boot time is slightly better than the SSD. Apps load much faster.

However, I'm not a happy camper due to BIOS boot numbering.

When I installed the NVMe M.2 drive, I pulled all other drives from inside and unhooked all of my externals.

For the first few boots, the M.2 drive was still listed as drive0, however, I noticed a slight slow down and checked my BIOS. The M.2 drive is now listed as drive8.

Normally, I wouldn't care, but, with the slight slow down it has prompted me to try and find a fix, which I was unable to find.

Things I've tried:
I have tried removing the internal drives and unplugging the externals, but, the M.2 is still listed as drive8. I even cleared the cmos. Re-flashed the BIOS. I even cleared the BCD entries to only show the boot drive.

I'm just at a loss on this one. Now, the slow down could be from something totally unrelated, but, the BIOS drive numbering now has me perplexed and I want to try and get that fixed, before I start thinking about maybe this M.2 drive is faulty. Any help would be appreciated.

Mobo: ASRock Z270 Pro4
 
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groves.damien

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Oct 24, 2017
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nvme/PCI-e based drives are handled a bit differently than drives on the IDE/SATA bus they are two different subsystems that are managed by the bios.

as i recall, the IDE/SATA subsystem comes up first and all attached devices are noted by the bios, which then checks the PCI-e/M.2 bus for devices

based on how the motherboard maker builds the bios, it may simply keep the original device ordering IE- SATA devices numbered first then PCI-e/M.2 devices, or the MB maker can have the bios then reorder the list and place the pci-e/M.2 devices first in the count.

whichever method the maker chooses for numbering in the bios,.. the device count makes no difference to whichever the boot device is as the active boot/C: device is manually selected by the user in most UEFI based bios's

since you don't specify the motherboard maker/model i can't tell you if this numbering is normal for your system board
or if you might be using the wrong onboard SATA ports for any sata/Mech based devices/card readers
 
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groves.damien

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Oct 24, 2017
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first of all, it's normal for a SSD to slightly slow down as it gets used, this is why some review sites only test a SSD after loading on files and using the Os for a while in order for the drive to enter it's "steady state" IE- he drive will no longer slowdown during normal usage.

i recommend you email asrock and confirm that the bios checks the IDE/SATA bus first for devices and numbers them first
before counting PCI-e/M.2 devices.

i suspect their reply will be much like i have mentioned in these posts. Either way i would be interested in what they say regardless
 
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scolla66

scolla66

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Jul 31, 2012
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10,510


Considering I installed the M.2 drive on the 14th, I don't think there should be a slow down as of yet. But, I'm not an expert. I will delve into other reasons why the slowdown has occurred. But, it's a fresh install of Win10 and not an image that I reimaged onto the drive. Win10 is flaky though and maybe that could be the issue.
 
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