On 12.0, .1, .2 running 5x280x with virtual memory of 56.6gb I'm getting
GPU #3 is going to use too high intensity (6), not enough memory, intensity value reduced (5)
when I set just one card to -i 6 also happens with -old 1
AFAIK this behavior is related to the available amount of GPU memory which limits possible intensity levels. Main/virtual mem should not be your problem here, if I am not totally wrong. Claymore stated that the memory requirements for the newer, faster kernels are higher.