Win 10 won't make half of a 4TB HDD available for use

[eripiomundus]

I just finished a PC build, installed Win 10, updated all drivers and bios.

Main components that might be relevant:

CPU: i7 8700K
MOBO: Asus ROG Strix Z390-e
SSD: 960 EVO 500GB
RAM: Corsair Vengeance 3200C14 16GB (8GBx2)
GPU: Asus ROG Strix GTX1080

I've got a Seagate BarraCuda 4TB SATA HDD installed. Windows didn't display the HD (whereas it showed in BIOS), so I went into disk management and tried to activate it. It was shown in three partitions - System reserved 549MB, and two unallocated volumes of 2047.46GB and 1678.02GB.

Right clicked the 2047.46GB and created a new simple volume. Windows now displays the drive, but trying the same with the 1678.02GB partition won't work - none of the options in the drop-down-menu are available for it except properties and help (there are no options under properties that seem to solve the issue. Should I have not made the first partition a simple volume?

 

[Colif]

is hdd formatted as GPT or MBR?

MBR can only access 2tb of space on a hdd, whereas GPT has no such restrictions.

Can you share a screen shot of disk management? Put it on imgur and share link here.

 

[eripiomundus]

https://imgur.com/a/55qyH

Yeah, you're right. It's formatted in MBR. How do I change it?

 

[bigpinkdragon286]

The system reserved partition on your drive may be required for your copy of Windows 10 to boot. The Windows installer has a bad habit of sticking boot information on drives the OS isn't on, from time to time. You may need to reinstall Windows with that drive disconnected, then connect and just wipe the hard drive after you finish installing Windows to the SSD.

 

[Colif]

curious why a Z390 board used MBR anyway, it should be set up to use UEFI boot method. Did you change anything in bios before installing?

Guy above is correct, win 10 has put the boot partition for the ssd on your 4tb drive, so converting it to GPT would mean PC won't boot.

most of his steps are right, but before you start the reinstalling I would go into the BIOS and check on the Boot tab of the advanced menu Page 3-20 of your manual - see here), make sure Launch CSM is Auto as then it should recognise the PC as UEFI complaint and use GPT as the drive format. Don't do this until you ready to run the installer or win 10 may not boot

sad thing is if it didn't have the system reserved partition on it, its just a matter of right clicking and choosing format

 

[eripiomundus]

Thanks guys. Update:

Before your post Colif I followed bigpinkdragon286's advice and reinstalled windows with the HDD disconnected. The problem remained. I was able to delete the smaller system partition without any interruption to windows, but could still only access the first 2TB.

Looked around for ways to convert to GTP and discovered that setting your bios to UEFI would do the trick. Checked the (then) current settings and they were:
Launch CSM - enabled
Boot device control - UEFI and Legacy OPROM
Boot from network devices - Legacy only
Boot from storage devices - UEFI and legacy OPROM
Boot from PCI-E expansion devices - Legacy only

I changed The boot device control to UEFI only and windows wouldn't boot. Just kept cycling back to BIOS. So I changed the storage devices one to UEFI only and windows booted plus it solved the issue - Disk management recognised all 4TB of the HDD. Only thing is the whole system is running really slow compared to before, and every single process in task manager shows up as 32-bit. Not one 64-bit process. Weird. So I'm going to reinstall windows again
with launch CSM set to auto as per Colif's recommendation. Also setting Secure boot to "Windows UEFI mode" instead of "other OS".

Might be running slower due to one of the updates, but not sure, so I'll just redo it all. Thanks again.

 

[Colif]

good thing your motherboard lets you choose which boot method to use on individual drives, as that is an good solution

UEFI boot matches GPT but it should be able to boot MBR as well. Perhaps if it had been set up as AUTO originally it might have worked better. Legacy boot method has no idea what GPT is. AUTO means PC will switch between both types to find boot partition.

Have not seen that 32bit behavior before, it is odd. Your UEFI is 64 bit (almost all are) and win 10 is 64 bit, so why the change? I can't find anything similar on Google. Its most bizarre

If you reinstall you will need to turn secure boot off as it will make PC ignore the installer USB. Win 10 will enable it again once installed.

MBR drives can only have 4 partitions and max size is 2.2TB, GPT drives can have 128 partitions and max drive size is way beyond current drive size - 18.8 million TB. I guess you could get there with raid and lots of drives/money. GPT created to fix MBR disadvantages. On MBR drives, the 1st partition has to be the boot partition, on GPT it doesn't care where boot partition is, it could even be on a network all it cares.

 

[bigpinkdragon286]

Changes to how BIOS boots should be made prior to installing Windows. Changes to whether your SATA ports use IDE or AHCI mode should also be made before installing Windows.

Unplugging the hard drive before installing Windows is not going to affect the hard drive at all. It just means that the Windows installer won't tie any important boot data to it, putting it on the SSD instead. You will still have to manually delete all partitions from that hard drive then convert it to GPT, which you should be able to find in the right-click context menu of Disk Management (provided all partitions are removed), and finally you can make one partition spanning all 4 TB of your drive, followed by formatting.