Question Internal SATA HDD is only recognized when another SATA HDD is connected ?

Dec 6, 2021
I have an Asus Z9NA motherboard with a variety of SATA drives attached. Yesterday one of them went bad (chkdsk initiated, finding unreadable sectors), so I decided to replace the drive.

I got a new SATA seagate barracuda 4TB (lets call it DRIVE A) and attached it to the computer via an extra SATA cable and transferred over the backed up data from another drive (that was, and has been, mounted on the same computer). I spend 24 hours dragging over the various data until it was ready to go. I then opened up the machine and removed the bad drive, putting the new drive in it's place.

Upon startup the new drive was not recognized in Windows 7 (under disk management). I opened up the case and reseated the connections. As I started it it up again, I had also attached another drive via SATA because I had to transfer some more data (lets call this DRIVE B). This time Windows saw DRIVE A, as well as DRIVE B. I transferred the data to DRIVE A and shut down the computer to detach DRIVE B, and restarted to make sure I could see DRIVE A.

Upon restart, DRIVE A again did not show up in windows. Another restart showed it in BIOS, and confirmed again it would not be seen in Windows. I then powered off, attached DRIVE B again, and started it up. Both drives were seen.

So it would seem that in order for DRIVE A to be seen, DRIVE B also has to be connected ?


More detailed information:

-DRIVE A is powered by one of those daisy-chained SATA power connections, sharing the cable with the DVD-ROM. The SATA connection is to the 6th SATA6 connectors (of which there are 6).
-DRIVE B is connected via SATA-eSATA cable to an external powered enclosure (called VoyagerQ), which attaches to the first of the SCU SATA connectors (SATA3), of which there are 4.

This work around seems to work, but it's so janky.

Anyone have any ideas why my 4TB drive won't mount in Windows without another drive mounted on the SCU port?
Last edited by a moderator:


Welcome to the forums, newcomer!

When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list them like so:

Include the age of the PSU apart from it's make and model and the BIOS version for your motherboard. What is the partition structure for the 4TB drive? It should be GPT as opposed to MBR.