I believe that you can still find a Z77 motherboard somewhere in SLS. This is the bare minimum that you can go for in order to use it.
Put your GPU into the second slot, and use a M.2 to PCIE adapter and plug it in to your first PCIE slot.
BUT before doing all this, make sure that your chassis meets the requirement for ATX size motherboard, cause in SLS i think you can only find Z77 in ATX size. I don't recall seeing a Z77 mATX size available.
In this way you will need to pay for a new motherboard and the new adapter. But if you think its very tedious and cumbersome to do so, then i would agree with the rest, sell the m.2 960 evo and buy a SATA based SSD. Which i kinda feel such a waste as you have a gift but can't be enjoyed lol.