Hi, thanks for reply. First of, rapid mode gives mi speed around 1500Mb/s read. And I can really feel it. Second, without it, it is sluggish kinda, and it is around 270Mb/s. (Not 540Mb/s like samsung advertise). I just tested it again today. And fast speed lasted around 3 hours. Then it just went down. No restarts. (Rapid still enabled) I wanna know what can cause it..