MacBook Pro - not liking new ssd

Hello,

I am having a slight problem with my Macbook Pro 13" Early 2011

My old ssd corrupted, used as a primary disk with 500gb storage (Samsung 840 500gb)

So I decided it was time for an upgrade anyway and ordered a Samsung 500gb 840EVO as after using Samsung's SSDs throughtout my household and only this time have I had an issue (this is much better than OCZ and other companies)

I managed to recover the files on my 840, and put them on my spare backup drive, and I can run from there like a dream.

However with my new ssd, whenever it is in the main HDD slot I cannot boot from it, and when I run it through where the disk drive used to be, I get the same issue (I cannot take my mac back to apple due to having the disk drive removed), however if I connect my new ssd via usb I can boot it up perfectly (I am writting this via it) but this is not very practical for day to day use, does anyone know how I could fix this so I can connect my ssd inside my mac (either in the main drive or via where the disk drive is (I dont mind!))

Thanks in advance,

Kind Regards,

˜Max