MPG X670E Carbon will not boot from Samsung 990

[dankjem158b02e1]

Hi All,

I put together a new rig today with the a MPG X670E Carbon Wifi motherboard and added a 2TB Samsung 990 Gen4 NVMe M.2 Drive to the build. My problem is that I cannot seem to get the BIOS to recognize the drive as the boot drive in UEFI. If I swap it over to CSM, it works that way and I can boot to my old 512 970 in one of the other M.2 slots, but that's only temporary, since I am keeping that drive intact for as long as I can move the rest of the data over to the new drive.

I've tried resetting the CMOS a few times to see maybe if there was just a mistake I'd made during the configuration, but from what I can tell, everything's working as it's supposed to be, except the BIOS refuses to see the 990 as a boot device unless I force it through the legacy option. I did read some threads about there potentially being a bug with the firmware that might be causing this somewhere, here on the MSI forums, but no good solution for it. From what I can tell, this M.2 drive should be supported by this board, and it recognizes an older 970 without issue, but I can't force it to boot to the drive in BIOS configuration I would prefer to use. There was a recommendation from somewhere else that I saw I should swap to the slot 2 for this drive, but that would require me disassembling more of the computer than I would want to, and I don't believe that it's a solution that would actually work, considering both slots both Gen 5. I don't want to rip a bunch of the new build apart to find out that solution won't work for me either.

I installed a fresh copy of Windows 10 Edu edition on the 990, but I doubt that has anything to do with it, since the 970 is running the same OS without any problem. Has anyone found a solution for this, or does this 990 just not work with this board for some reason? PCpartpicker didn't flag it with any compatibility issues. The 990 pro should be compatible with this motherboard. I am at a loss and it's late, so I'm going to hit the sack, but I am hoping someone knows a good way around this little issue.

 

[citay]

I installed a fresh copy of Windows 10 Edu edition on the 990, but I doubt that has anything to do with it, since the 970 is running the same OS without any problem.

A modern BIOS can be in two modes: Legacy/CSM (Compatibility Support Module) and the newer UEFI (Unified Extensible Firmware Interface) mode. Since all BIOSes are UEFI BIOSes "under the hood" nowadays, naturally they work best when set to UEFI mode. But also, every modern BIOS can be set CSM/Legacy mode, in order to behave like an old BIOS from many years ago. This is so it can work with older operating systems which have no or only limited support for UEFI, such as Windows 7. The problem lies in the fact that switching between those two BIOS modes after you have installed Windows will make the boot process fail.

When Windows detects a BIOS in CSM/Legacy mode during installation (or on old boards, an actual legacy BIOS), it prepares the boot drive to have an MBR (Master Boot Record). When it detects a UEFI BIOS during installation, it will prepare the boot drive with a GPT (GUID partition table) instead. That means that the BIOS set to either mode (CSM vs. UEFI) will only boot from a drive that was prepared accordingly for that mode (CSM needs MBR, UEFI needs GPT). That's why you need to do the quick MBR to GPT conversion for your boot drive once your BIOS is set to UEFI mode. Alternatively, you just do another fresh install of Windows.

You might be thinking, but how about just setting it to CSM mode? Well, Windows 11 will require the BIOS to be in UEFI mode. And Windows 10 support ends in 2025, then we will all have to upgrade to Windows 11 anyway. So by doing the conversion from MBR to GPT now (or doing a fresh install in UEFI mode), the BIOS can stay in UEFI mode and you would be ready for Windows 11. If you set the BIOS to CSM mode for a quick fix, you'll only have problems later.

Now, there's a couple things to keep in mind here for a fresh install.

First of all, with a BIOS in UEFI mode, the drives are not really what's booted anymore, instead it boots the so-called bootloader that's on the drive. For Windows that's called the "Windows Boot Manager" and it's further down on the boot order screen, in a submenu "UEFI HDD BBS Priorities":

But you never really change the boot order manually here anymore. With an UEFI BIOS, the Windows installer can add itself here during the installation.

But it's important to only have the one drive hooked up that you plan to install it to. Because when you have several drives hooked up already, sometimes the Windows installer can get confused and put the bootloader (Windows Boot Manager) on one drive, and the actual Windows files on the other drive.

So what you do is, having taken out all the other drives, you press F11 for the boot menu to boot from a USB stick that was prepared with the latest Win10/11 Media Creation Tool, as mentioned in step 3) here. That is, if your 990 is listed under Settings\System Status, this is the bare minimum for it to work.

 

[dankjem158b02e1]

I am just going to pull the drives and re-install. Thanks for the extra info. Something else is going on though, since that new installation is already set to GPT partition, it is however not marked as a bootable partition within Windows 10 (that I can see from Disk Management.) I didn't plan on staying on the legecy configuration, or else I'd have just left it and not made the post. Windows 11 is coming for me, co-pilot be damned, I suppose. I was also having issues with DIMM detection and had to reset the CMOS for it to read the DIMM and see the 2 TB 990, until then the only drives that were visible was the older 970 that had the MBR and some off-brand M.2 drive that I only used for storage.

I've done multiple personal builds and never run into this issue while carrying over hardware in the past, I guess I just got lucky and didn't have to swap the between legecy and UEFI configurations in the past while running installations. I suspect you're right, the boot loader got confused. I didn't catch the inital boot on the new drive while it was finalizing the installation. As a result it booted to the original drive, I suspect that is where I made my mistake while trying to walk the fine line of having two, bootable windows partitions going at once without having one finalized. I think it saw the other MBR and used that instead. Why windows would allow the bootloader to put on another drive just seems a bit crazy to me, but that does seem to be what happened.

I keep an updated Windows installer on a thumb drive just for such an occassion, so I guess things could be worse. Thanks again for the help.

 

[fd-sk15cd02e7]

hi Dankjem - did you ever get it fixed ? I ran into exactly same problem

 

[xrodne152202d4]

This is how correctly setup disk for W11 looks like, that 100MB EFI partition is what is telling system from where to boot and C drive is actual boot partition with W11.