The solution here is NOT the right one, it works by side effect. I found out that with some motherboards, “RAPID” technologies (Intel or Samsung) were causing freezes.
* Samsung : in Samsung Magician, disable RAPID option
* Intel : Uninstall Intel RAPID software

Disabling AHCI indeed disables the RAPID option on Samsung Magician, but this is a bad solution because you loose many of the benefits of the SSD wihtout AHCI.

Hope it helped.