HDD not recognized GPT UEFI

[Tourniquet]

Hello,
I've got an Asrock Fatal1tyZ68 Professional Gen3 Mainboard. Before I had Windows 8.1 installed on a small 512GB HDD with MBR and everything worked fine. Now I've switched to a 6TB HDD. The Problem is I had to switch to GPT because of the size.

The strange thing now is. When I unplug and replug the HDD it is recognized as a bootable UEFI option. When I restart it is not recognized as an UEFI option anymore. When I try to boot the HDD without the UEFI option I only get "please select a bootable device".

The workaround can't be that I have to unplug the HDD everytime I need to restart!?

What can I do?

 

[KYHI]

if you can disable legacy support via the bios...
set drive controller as AHCI

see if that helps

 

[Tourniquet]

No there is no way to do that.

Drives already set to AHCI.

 

[KYHI]

was this a clean install to the New 6tb drive ??