Its not the temperature you have to get right, its the timing.
From my experience, use water that has just
been boiled, make sure the egg is totally immersed in water. For
eggs that you took out from the fridge not long ago and still cold,
use 8 mins, for eggs you didn't refrigerate or took out from the
fridge overnight, 6mins. For regular sized eggs 55gm and below, 5
mins, for large eggs 66gm and above, 6mins. If combination of large
eggs unrefrigerated, 6mins. For regular sized eggs refrigerated,
aiyah you get the drift. 