GA-790XTA-UD4 with 4tb HDD Showing 1.6tb even in GBT mode

[gbuser2013]

Currently I have follow following drives connected to the motherboard
1. SSD 128GB (BOOT) (Marvell Controller)
2. SSD 128GB (Marvell Controller)
3. HHD 1TB
4. BLU RAY

BIOS Setting in motherboard are set to ENABLE SATA & AHCI on all ports

Now I am trying to connect a new HDD 4.0TB (just for storage not boot) but in windows disk manager it only shows up as 1.6TB  (using GBT).

While trying different settings in BIOS I switched the SATA to IDE on all ports and disabled AHCI, this time windows started showing full 3.7TB space in disk manager!! I am guessing its a driver issue? as during boot the AHCI scan screen shows the drive to be 4TB as well 

I noticed that there is a 3TB unlocker for newer mother boards but not this one 

OS: Windows 8 64-bit
BIOS Ver: F4A

[Tiger]

Resize GPT disk with free partition manager software:
http://www.partition-tool.com/easeus-partition-manager/resize-gpt-disk-partition.htm

The Windows built-in disk management provides limited features for GPT disk management. It is not possible to resize GPT disk with Windows Disk Management freely. A third party partition manager software like EaseUS Partition Master is necessary to resize GPT disk.

[gbuser2013]

It is not an issue of resizing partition ...Windows is not even picking up the unallocated space! however I did try downloading the tool you suggested and it doesn't show space beyond 1.6Tb either 

As mentioned before when switching to IDE mode in BIOS windows starts picking up complete 3.7TB .

[mikeyb5753]

go to the drives website to see if theres a tool to correctly initialize the drive.  I have a seagate 3TB drive and need to use the seatools discwizard program or I can only access 2TB

[gbuser2013]

Didn't find anything on the drives website.

Is there any possibility that 3TB+ Unlocker Tool created by Gigabyte would include 790 chipset motherboards?

http://www.gigabyte.us/microsite/276/3tb.html