You mean one power cable right?(daisy chain) I guess you can get a separate one and see if this will change anything.
Another thing you can try is to use some third party tool that can show you what is accessing the drive.
Is the HDD just spinning or it makes some unusual noises?
In case the HDD is just spinning up, you can go to Resource Monitor and see if there is high Disk Usage and what is causing it.
Apart from that, you can:
- Attach the HDD with different cables to a different port.
- Test the drive. If there is something wrong with it, you need to back up the data stored on it: http://www.tomshardware.co.uk/forum/282651-32-best-diagnostic-testing-utility
You mean one power cable right?(daisy chain) I guess you can get a separate one and see if this will change anything.
Another thing you can try is to use some third party tool that can show you what is accessing the drive.