I recently changed from MBR to GPT and now my system takes over an hour to boot. I suspect a partition arrangement problem. I'm running Windows 10 on a RAID 5 array. Here is my current partition setup: enter image description here enter image description here

I used AOMEI to do the conversion, and for some reason it appears the system partition was placed at the end instead of the beginning of the disk. The first FAT16 partition is apparently a Dell Utility Partition. I don't want to disable my hardware diagnostics if possible but I may have to. How can I remediate this problem so my system will boot properly? It doesn't appear that AOMEI will allow me to move the FAT32 partition. Can I move things around and recreate it at the beginning of the drive? This post suggests that my partitions should be arranged differently. To execute this, I suspect I will have to:

1. Resize Partition 3 to provide working room
2. Move Partitions 2 and 3 to the right, leaving unallocated space at the beginning of the drive and delete partition 1
3. Create a new 100mb EFI FAT32 system partition at the 1024kb offset
4. Delete the existing FAT32 system partition at the end of the drive
5. Create an MSR partition of 128mb at 103424.

Optionally, to reclaim unallocated space, move the other partitions back all the way to the left and expand C back to the end. Is this correct? Probably best to do this through diskpart?


11-28-2015: I contacted AOMEI and they responded with this:

"The problem should be unrelated to the order of these partitions. We guess it might be RAID5. Maybe you may try to repair system via WinPE or system installation CD."

Please Note that the system was running fine on RAID 5 prior to changing from GPT to MBR. Also, I already ran the repair with WinPE and that's what created the Windows Boot Manager entry in the BIOS under UEFI.

  • What makes you think the slow down is because of the layout of the partitions?
    – Ramhound
    Nov 28, 2015 at 3:04
  • It's just a guess, really. I'm not sure what else it might be. Do you have another idea? It's very strange. There's a little more information in my initial post: superuser.com/questions/1006384/… Nov 28, 2015 at 3:17
  • Here's a discussion that suggests that the order of my partitions may be the problem: technet.microsoft.com/en-us/library/hh824839.aspx It appears I would need to add a Windows RE tools partition at the front as well. Is that what the Dell Utility Partition actually is? Nov 28, 2015 at 5:28
  • The Microsoft page to which you've linked just specifies a recommended order; it does not say that the consequence of violating that order will be a slow boot process. In theory, it should make very little difference, since the files to be read from the ESP are small and the performance differences from start to end of a disk are slight. Chances are something else is going on, like a misconfiguration of the EFI-mode boot loader, mis-aligned partitions, or a driver problem.
    – Rod Smith
    Nov 30, 2015 at 1:05
  • Agreed. I read on another page about slow boots related to that issue as well, but I know that's not it now. I have now isolated the problem to the Credential Manager (lsass.exe) file. I'm still not sure what to do about it, though, other than disable it, which doesn't seem right. See my other thread on this subject: superuser.com/questions/1006384/… Nov 30, 2015 at 2:21

1 Answer 1


I have discovered the system will start in Safe Mode. Consequently, I did some further troubleshooting and have isolated the Credential Manager service as the cause of the slow boot. Still not sure why, but that's definitely involved, if not the direct cause. See this thread for more details. I had mistakenly assumed that because the problem followed the move from MBR to GPT that this was the cause, while in reality, the problem just became obvious when I rebooted during the change.

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