I'm planning to use a second Samsung 1TB ssd instead of my actual HDD in my Dell Inspiron 15R laptop (I already got a 256gb one installed in the optical drive bay). I would go for the 850 Pro but I noticed that its dimensions are bigger than the HDD. The 840 Evo is about the same size. Can this be a problem or is there enough room for slightly bigger drives as well? Cause if not then I'll need to choose the 840 Evo.