Laptop won't detect two 3TB external hard drives at same time

[James80]

I have an MSI GX660R running Windows 7, which has two USB 3.0 ports on it, and purchased two WD 3.0 3TB external hard drives to store all my media.

After putting all my media on one of the hard drives I conected the second to copy all the stuff over so I would have a backup, however when connecting the second hard drive I noticed that I couldn't see it in My Computer. Thought it must be a problem with the hard drive but when its connected on it's own or with other hard drives that are 2TB and under it's fine.

Cant find anything on the web about this, hope someone can help.

[smirnoff_rules]

right click on computer and goto manage A new window titled Computer Management comes up.
Select Storage from the left hand side by clicking it once, then select Disk Management and see if the drivers there and if it needs formating in there or drive letter changing

[James80]

Thank you so much, been strugling with this for days, it was't being assigned a drive letter for some reason, but followed your instructions and had it working in minutes.

Thanks again.