To bring an end to this thread and some clarity to anyone who may read it in the future:
I didn't get around to trying BIOS f9, I had tried bioses from f3-f8 and x02-x08c all with varying results none of which worked with 4 dimms at 2400mhz.
Moved over to an z97 xpower ac, posts fine, tunes fine, benches fine and passes memtest fine.
So I can only presume the z87x-oc either didn't like the ram or couldn't (for what ever reason) hold 4 sticks at 2400. That or the board is faulty.
Now I'll be going back to restest my other RAM that failed on that board (some tridentx) and see of they pass with the xpower too.
I didn't get around to trying BIOS f9, I had tried bioses from f3-f8 and x02-x08c all with varying results none of which worked with 4 dimms at 2400mhz.
Moved over to an z97 xpower ac, posts fine, tunes fine, benches fine and passes memtest fine.
So I can only presume the z87x-oc either didn't like the ram or couldn't (for what ever reason) hold 4 sticks at 2400. That or the board is faulty.
Now I'll be going back to restest my other RAM that failed on that board (some tridentx) and see of they pass with the xpower too.