Divide by 8 then you know how many KB/s you get (but you need to reduce your result by 10 or 20 % due to overheat)
256 : 8 = 32 -6/7 = 25-26 KB/s (others correct me please if I'm wrong)
128 : 8 = 16 -3/4 = 12-13 KB/s (others correct me please if I'm wrong)