Inspiron 3847 won't boot with 5TB drive?

* How is the internal 5TB connected using what port and cabling? Assuming it is connected to a motherboard SATA port? If yes, boot into the BIOS setup
* Go to Boot
* Make sure that the 5TB is last in the Boot Device list and UEFI:Windows Boot Manager is first

* For the external 5TB, in the same Boot section
* Disable USB Boot Support
* Press F10 to Save and Exit

Are you booting in UEFI? The Biggest advantage of UEFI is the ability to use large disks (over 2 TB) with a GUID Partition Table (GPT). Legacy has the limitation of not being able to use big drives so that's probably why it won't boot.

UEFI Secure Boot is not the issue.  GPT partitions vs MBR partitions are the issue. Windows 7 or Vista does not support Secure Boot UEFI but does support GPT Booting. The Booting REQUIREMENT is 64 bit OS.   GUID Partition Tables (GPT) can define drives larger than 2.2TB. You can use GPT today on any Windows 10/ 8.1/8/7 and Vista system as a non-booting data drive. Windows can only boot a GPT partition.

Windows and Greater than 2TB drives:

• Windows 10/8/8.1/7 and Vista GPT Greater than 2TB single partitions
• Windows 10/8/8.1/7 and Vista can only boot GPT on systems with UEFI BIOS
• Windows 10/8/8.1/7 and Vista can mount a GPT non-booting data drive
• Intel RST device drivers before v10.1 do not support 3TB disk drives
• Windows systems with Legacy BIOS and MBR boot drives are limited to 2.2TB partitions
• Windows XP does not support GPT
• Windows XP sees a 3TB drive as 800GB on boot or data drives.

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@speedstepwrote:

• Windows systems with Legacy BIOS and MBR boot drives are limited to 2.2TB partitions

 

 

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This is what I meant to suggest in my post