Discussion disable NVMe drive in BIOS - motherboard support

MG2

Junior Member
Nov 9, 2022
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You might have wanted to disable or disconnect an M.2 drive, for whatever reason. Maybe for installing a different OS or for testing or privacy purposes...
Unfortunately, while motherboards often let you disable SATA ports, support for disabling M.2 slots in BIOS is almost non-existant.

So, I have contacted motherboard manufacturers regarding this feature and I want to share my findings.

ASUS informed me that their Z690 line has some limited support for this: it lets you enable/disable one M.2 slot. Looking at the manual, it's the one from the chipset.

ASRock doesn't have this as a standard feature, but they told me I can contact them and they'll send me a custom BIOS for my mobo with this feature enabled. And it would work even on older models, like AMD B450 and Intel Z490. They didn't say anything about it being limited to specific M.2 slots (like in the Asus case), but they did say it wouldn't work on PCIe slots with PCIe-M.2 adapters.

Gigabyte just gave me a standard answer that they'll consider it. MSI and Biostar didn't reply so far.

So, if anyone has an ASRock mobo and is interested in this feature, please contact them and let us know how it goes. Those with newer ASUS boards can also try it for that one slot.
And it would also help if more people request this feature from motherboard manufacturers. I think it should be standard and it's more needed for M.2 than for SATA drives, because the former are harder to physically disconnect.
 
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sdifox

No Lifer
Sep 30, 2005
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Why would it be hard to disable an M.2 slot connected to the CPU?

Just curious because your reply sounds like you know a bit more about this and maybe the specific reason?
The whole point to PCIe connection is to minimize delay. Adding anything else there to disrupt the connection is counter productive. Op is better off removing the nvme drive to do what he wants. Or change bios boot order setting and remove the drive from the list.
 
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OlyAR15

Senior member
Oct 23, 2014
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Yes, it is such a good idea to go to the expense and trouble of buying and installing an M2 drive, only to not use it. Makes perfect sense. Why didn't anyone think of this before?
 

zir_blazer

Golden Member
Jun 6, 2013
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The whole point to PCIe connection is to minimize delay. Adding anything else there to disrupt the connection is counter productive.
This is one of the worst descriptions about how things works that I have ever read...

Intel 12th Generation Intel Core Processor Datasheet Volume 2 of 2 mentions at section 6.24 Link Control (LCTL) for the D6:F0 Device (The PCIe Root Port that controls the 4x lanes that are usually going to the Processor attached M.2 Slot) that there is a Link Disable (LD) Bit that actually disables it (And most likely it is PCI Express standard, so I expect every existing PCIe Root Port to support it). So a BIOS option to disable that specific Port would just need to flip that Bit.

And yes, there are use cases where you may want to disable a PCIe NVMe SSD without physically removing it.
 

zir_blazer

Golden Member
Jun 6, 2013
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No, ASPM is separate.


PCIe root and downstream ports have link control register that can be
used disable the link from software. This can be useful for instance
when performing "software" hotplug on systems that do not support real
PCIe/ACPI hotplug.

Device Disable
Auto—The device is automatically enabled at server boot.
Disabled—The device is not automatically enabled.

PCIe Power Management (ASPM)
Auto
Disabled
L1 Enabled—The device's link enters a lower power standby state at the expense of a longer exit latency.
 
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MG2

Junior Member
Nov 9, 2022
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The ASRock rep confirmed that their custom BIOS works for disabling any M.2 slot, including those from the CPU. And as I said in the OP, they told me it would work on every new-ish motherboard.

ASUS mobos are limited to the chipset slot only currently. But I imagine they and all other manufacturers could also enable it for other slots with a new BIOS. Unless ASRock added some special hardware tweaks that allows them to do this, but I doubt that's the case.
 
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MG2

Junior Member
Nov 9, 2022
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Meanwhile, I found this option also in the ASUS Intel 700 series manual, in the same section (PCH Storage Configuration) as for Z690, but with one difference:


I hope that's just an error and that the toggle isn't limited to SATA M.2 drives.
 

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