New hard drive falls ofline in windows 7

I had a problem a while back basically I started to lose drives hard drives windows explorer.  Often it would give me the message that basically said format before use.  Or it would just be unavailable.  In command line it said drive not available (simular to when you try and access a removable drive and no drive is present).

I reboot the system (power off/on) and the drives come back online.

My computer consisted of WD 1TB black, WD1.5TB Green and another 500 gig drive

In a process of elimination I replaced the drives, cables, power supply motherboard.

New PC, new drives : 2 x 1 TB WD Blue + the old 1.5 TB WD Green

I finaly got the system semi stable and it started to happen again.  This time a new 1TB Blue D drive falls ofline.

It is like the drive goes to a hibernate mode.  I have set up power mode to never shut the hard drives down.  

I am begining to think I have missed a software thing in windows as almost all the hardware is new.

Can anyone help me.


As a recommendation, test the drive using the DLG tool this will allow you to identify if there’s an issue with either of the units.

Link to DLG tool:

I have performed the quick test on all drives, no faults found.

I am going ot run the extended test now.

2 Questions :

1.) What is the minimal safe voltage for the 12VDC rail?  Although I have changed everything I am wondering if I haven’t changed it for the better.  My ASUS sensor program shows a maximum voltage drop down to 11.68 or so

2.) While the Data Lifegaurd is working is it normal for windows explorer to lose the drive from its drive list?  I have seen it diapear and reaper once the test is completed.

Thank you