Why does only 1 dimm slot work in my new MB?

I hope someone has had this experience before and can help.

 

I've put together a new build with i7-4790 and a MSI z97 gaming7 MB. The weird thing is that the board will only post with 1 dimm slot in use. When I add dimms to the other 3 slots or even a second, it only power cycles with no beeps. No post. Note that ram is not in QVL.

 

I've tried each of the 4 pcs of corsair ram I have in each of the 4 slots individually and every time it boots up fine to eliminate a bad stick, plus these dimms were pulled from a working pc. I've even tried a pair of different corsair ram ddr3 dimms and got the same results as above. Only 1 dimm slot would ever work. MSI told me that it was either a problem with the motherboard or the memory controller on the cpu but couldn't be certain.

 

I ran a cpu diagnostic from Intel's website and everything passed to test the cpu. Swapping the cpu to another board to test it itself doesn't sound fun.

 

MB BOIS is the latest, CMOS reset, ram firmly seated etc ...

 

If you can't think of anything else for me to try, would you RMA the board and CPU or just the board?

 

Thx in advance !!

For non functional dimm slots i would check the socket pins for damage first.