Id suggest 1.67v is too high anyway.
Is that corsair kit listed as compatible for the board?.
You could try bumping vtt just a little maybe to 1.1 v
Those arent very tight timings for 1866 but you could use sisoft sandra or aida 64 to see what the secondary timings are on the memory and enter those timings manually.
Id also clock down the cpu a bit even go to stamdard 3.3-3.7 and see how the memory behaves then.
How does it perform with just 2 sticks?
Not much point in trying a stable overclock and doing memory tests at the same time, at least not until you have the memory stable.