Have you checked to make sure the memory is compatible with your motherboard?
I was told it was when I bought it - although looking on the web it looked like it was compatible with the smaller version of the same model RAM (i.e. 4GB rather than 8GB).
However, I have just done a 48 hour memtest86+, which has finally kicked out about 150,000 errors across both chips. I'm RMAing the chips and hoping that's the answer.