Abstract: The method of providing a desired motive force for one or more rams of a subsea blowout preventer as a function of a desired pressure differential across one or more pistons on the subsea blowout preventer when the desired pressure differential is higher than the gauge pressure of the accumulators supplying the pressure, comprising providing one or more pistons connected to the one or more rams, the pistons having a distal side and a proximate side with respect to the rams, providing a first pressure from the accumulators to the distal side of the pistons, providing a tank to contain a second pressure less than the ambient pressure of seawater at the location of the subsea blowout preventer, providing a pressure reducing valve which exhausts into the tank and reduces the pressure on the proximate side of the one or more pistons to proximately the difference between the desired pressure differential and the first pressure further comprising that the pressure differential across the one or more pistons is proxi