Grumpy_Mike:
That is probably because you did not have enough decoupling capacitors on your power supply. A couple of caps would have saved you from buying a 6A supply.
Seems I misread the current draw for the strips. With the 6A supply connected I measured 3A draw at %100 white. Stats were correct, I was just not accounting for the correct strip length.
3A from a 1A supply. Flickering should have been the least of my worries!