Interesting, Do some trouble shooting, set the RAM at stock if you haven't already and run that again.
Next take out one stick and run it with just the one stick in, put that stick back and take the other out, run it again, then put that stick in the other 3 slots.
What you are looking for is a defective stick or a defective slot, if you still see this issue after you have done all that send the CPU and / or Motherboard back on RMA.
Holw long have you had the CPU, MB and RAM?
That's the plan of action when I get home tonight.
I took delivery of all three yesterday from OCUK, along with the GPU and an SSD