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PC doesn't boot after switching from AHCI to RST in BIOS


Hello everyone, I'm desperate for help

My system:
M.2 #1: Intel P4500 NVME (boot drive (AHCI), Windows 10)
SATA: 4TB mechanical HD

To this already working PC, I've decided to add an Optane P1600X M.2.

So I Installed the Optane card in the available M.2 #1 slot of the mobo,

The RST Driver was already installed in Windows with its icon shown in the taskbar, but I read I need a newer version in order to use the Optane APP with the new P1600X (I tried installing the newest RST driver, and it told me to first enable RST in the BIOS).

Entered the BIOS and Changed from AHCI to RST, for both M.2's - #1 Optane P1600X and #2 P4500 NVME (my Windows boot drive),

Restarted the PC, and ever since the PC doesn't boot… It's stuck in some initial loop, without reaching even the BIOS, nothing shown on screen, the CPU fans speed changes as if something happening: Speed up with the HD LED change from blinking to constant on, then slow down with the HD LED off, and the process repeat – for 10 hours as of now.

I'm afraid to interrupt it. Afraid I was supposed to change the bios RST only for the P1600X, and I hope switching the boot drive also to RST didn't broke the P4500… nor the SATA 4TB HD, which I set for Windows backup and snapshot to use

I'm writing this from an old laptop. Please teach me what happened, and what to do.
Thank you very much!

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Super User

1. I've changed the SATA mode in both directions,  in Windows SAFE mode many times. Still, I advice you to have backup of the system drive.

2. SATA RST mode doesn't affects NVMe drive, so you may leave the P4500 in AHCI.


Good luck with your tests.



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6 Replies
Super User

Since you have already fast boot drive Intel P4500 NVME,  it not clear to me, why you want to install an Optane P1600X drive. This drive is intended to serve as a boot drive for modern data center. You can not use this drive to accelerate the HDD. In order to accelerate the HDD, you may use an Series M10 Optane drive.

Any way, while switching SATA mode from AHCI to RST, you corrupted the boot part on the M.2 drive. I suggest that first, set the SATA mode back to AHCI. 

If you have your system drive backed (as I understand you have on your HDD), you may restore it from backup. If not, try to restore Windows to the Last Know Good Configuration after booting into Windows Advanced Menu.


Once your computer is booting again, in order to change SATA Mode without destroying Windows boot, Windows must be set to SAFE Boot Mode. While in Windows, press Windows key + r. Run msconfig .  Chose Boot tab and enable Safe boot. Reboot your system. 

Now you can change the SATA mode to RST. Save the new BIOS settings and exit to Windows.  While in Windows, press Windows key + r. Run msconfig. Chose Boot tab and uncheck Safe boot

Reboot your system. Now your system is bootable in SATA RST mode. You may continue to enable your an Optane P1600X M.2.

Please read also Can Optane 1600X be combined as caching drive in hybrid volume with another NVMe SSD?

Hope this will help




Hi Leon,
Thank you very much for all your help
I wish to learn something before I proceed, please

There are 2 sotrages devices attached to both M.2’s, currently all in AHCI mode:
M.2 #1 – p1600x 118gb
M.2 #2 – P4500 NVME (boot drive, windows)

In order to install in Windows the newest RST driver & OPTANE app, I have to switch the BIOS from AHCI to RST.
My question is, as I will use the Safe Boot methode you tought me, do I need to change to RST for both storages? Only one? (which one?)

I don’t yet understand RST enough, and wish to learn, so if you could explain just a bit (and/or refer me) I will very much appreciate it

Thank you again (and again!)


Thank you very much Leon! I'm eager to read and try your suggestion!

Super User

Hi @Teflon 

To answer your question: "...I need to change to RST for both storages? Only one? (which one?) "  SATA mode affects all SATA drivers. So, if you want use Optane acceleration, you need change SATA mode from AHCI to "Intel RST Premium with Intel Optane" . But since you have an Asus board, I suggest that you should ask for the method to enable acceleration in Asus Support Forum. You may read also Asus User GuideOn this page you may find answer to many questions related to Optane on Asus board. 

Any way, if you want to change the SATA mode without corrupting Windows, do it is SAFE mode.


But again, I want to emphasize that I don't understand why you are going the P1600X drive. As I explained to you already, this drive can't be used as accelerator for you HDD or NVMe SSD. Please read first two sentences in my post above.





Thank you, I read and understand,
I just figure as long as I have the hardware might as well try and put a use to it, and I’m hopping it’ll beneffit at least some use cases, and even if not, It’ll be a learning experience (as long as I won’t break anything!). In my next build, I will install the OS on the Optane drive.

The guides are helpful, though I have a mix situation, because the BIOS is set to AHCI, while the RST driver is installed in Windows – which prevents me from installing the Optane app. And since RST driver can’t be uninstalld, in order to use the Optane app, I must change the BIOS from AHCI to RST, and go with the second rout in the guide.

In my case, after switching the SATA mode to RST, two submenues appear:
M.2_1 PCIE Storage RAID support - for the P1600X
M.2_2 PCIE Storage RAID support - for the P4500
In the guide there's only M.2_1, but I need to choose for both whether to enable or disable. That's why I asked should I enable both, or each and which.

I just want to understand the consequences before going through with this,
Can I reverse the process the same way, and use safe boot to switch back the boot part of the P4500 from RST to AHCI?

Before you tought me how to change SATA modes, I thought I’m stuck with AHCI and unable to use the Optane app without fresh windows installation. So I looked for a way around and found an option to set the P1600X as level 2 cache (read and/or write) with a third party software PrimoCache.
Is Caching what the Optane app does too?

I read about the Intel Optane algorithem, am I correct guessing without using the app, I won’t beneffit from it trying to speed things according to my use case? Or does Windows does that by itself when given a large level 2 cache?

Thank you from the bottom of my heart Leon.

Super User

1. I've changed the SATA mode in both directions,  in Windows SAFE mode many times. Still, I advice you to have backup of the system drive.

2. SATA RST mode doesn't affects NVMe drive, so you may leave the P4500 in AHCI.


Good luck with your tests.