You should not open them - return them immediately and get the 850 Pro - they're about to be released (should have been released on Monday but got delayed).
840 Pro is a great SSD but last gen.
Also, I concur w/ people who say RAID-0 SSD for the OS is almost pointless.
I used to have RAID-0 Corsair ForceGT 120GB SSDs. I now just have one - still performs great and in fact boots somewhat faster from what I can tell (LOL).
RAID-0 is a total farce for home-use --> even...