WD GPT 4TB internal HDD turns into RAW after 2.27 TB storage

For the 4TB drive, maybe try to separate the drive to 2 partition.
Partition 1 to up to 2TB
Partition 2 to use as logical partition.

Not sure if it works or not.

Eric.

If I remember well, 5 years old MB where legacy with a UEFI support for drives. They used to call hybrid Bios.
Try to enable UEFI drive support on BIOS and boot. If it boots, go to disk manager and extend your partition to the end. This way you don't need to reinstall win 7.

thanks guys, your help is really appreciated
@megahertz078 @jumanji
i will try to enable the UEFI (just after i finish writing zeros to the HDD, it takes ages :))

what i did not mention earlier is that i actually dis-attached the HDD that contained the OS & all the other HDDs (by the way one of them was 3 TB & it was working) & made a clean install of win7 on another HDD.
Then attached the new OS & the 4TB storage only to MoBo (performed almost all important updates & currently working on optional updates)

i will test the above & come back to you

i have the BIOS update downloaded but i am keeping this as last resort since:
1- it was working before
2- i can not revert back to previous BIOS versions if -god forbid- any thing happens

- Normally when you launch the BIOS update from BIOS options it has an option to save the current BIOS.
- This link has the latest BIOS and also the old ones. https://downloadcenter.intel.com/dow...?product=50098
- I always install the latest BIOS.

* i enabled UEFI but no dice same issue

* i wrote zeros to partition (approx. 1678 GB) using minitool:
in Win7 CD it shows as full capacity
also BIOS sees it as 4TB
& within OS it shows 1678 GB (& the rest of the space that should show as un-allocated in disk management is not even there!) & i am unable to restore the 4 TB again

* i am almost sure it is an issue with GPT Tables. i will write zeros to it using 'WD life guard' then if this doesn't fix it i'll have a go on some thing like 'Gparted' any body with experience?
* if any one can read the 'CrystalDiskInfo' file that i have attached it will be extremely helpful in determining the problem

If its sata3 is it on a sata3 controller not sata2?

It is SATA 6Gb/s and if OP is using SATA connection, he should connect it to one of the two SATA 6 ports in the motherboard. I would think the OP is aware of this.

While trying to resolve this problem the OP is well advised to adhere to SATA connection to the motherboard since traditionally people have reported many problems with eSata and Windows 7.

On the suggestion of ThrashZone, I entirely agree that one will be better off with 2TB drives rather than >2TB drives especially with old motherboards. Two 2TB drives is definitely better than one large 4TB drive ( I have consciously avoided >2TB drives throughout.) Here two birds in the bush is better than one that flies .

connected to a 'SATA' port instead of 'e-SATA' same situtation