Sorry missed that Now looking up your board manual (http://dlcdnet.asus.com/pub/ASUS/mb/...144.1459005269 see 1.2.4 page 23/186) the red slots are the primary ones (1&3) so suggest testing each stick in the red slot nearest the CPU and if errors come up with either stick then test them again in the next red slot if there is still errors then the stick/s is/are bad, if there are no errors with the second testing then it points the finger at the first slot, but like I mentioned previously that would be most unusual.

It is tedious but worth it if it finds where the problem lies.