Extending my hard drive on laptop

I was very surprised by the good performance of the board from 30 to 50 MB / s read and 24 to 27 MB / s write following file sizes (more is bigger and it goes fast). Used only on my laptop (small SSD) to store movies and images.
Also should be excellent for backups but I have not had time to test it, the card does not work after 5-6 days of use.
I do not despair because I have sought reimbursement of the card and receipt of it I would buy another card MS Pro Duo HX, too powerful !!!