Oops, spoke too soon.
Tried memory settings of 2.5, 6, 2, 2, 7.8ms (going down the options list) but got reset when loading Windows. Reset to using SPD timings and no problems loading windows.
From the Kingston site the memory should accept timings of 2,6,2,2 without any problems at DDR 400 and so should the corsair. Most likely will have to go through pulling some of the memory out and testing that way. Oh fun........