Alienware mx17 R5

Hello peeps,

I'm planning on upgrading my mSATA ssd (64gb as installed when I bought the system) into 2 options.

1. Samsung 840 Evo 520gb mSATA   or   2. Samsung PM841 512gb mSATA

I'm leaning towards the first option (Samsung Evo) but I have read that it is a bit larger in size than option 2 which is 69.85mm (Samsung Evo) vs 30mm (Samsung PM841) = 39.85mm shorter.

http://versus.com/en/samsung-pm841-msata-512gb-vs-samsung-840-evo-500gb

Have anyone tried this before? I have concerns that it wont install properly or worst doesn't fit in the area of mSATA (compatibility wise both can be used "did my research already", so no issue on this) just the size issue for the price of both mSATA SSD is a bit much and I can't just throw them away if it can't be installed.

If anybody have tried, Please help.... THANK YOU !