Since you've determined that the power supply is a 700W dual rail, what does that make the maximum output power?

700 makes the maximum output power.

Explanation:

In physics, power is the rate of doing work or of transferring heat, i. e. the amount of energy transferred or converted per unit time. The output power of a motor is the product of the torque that the motor generates and the angular velocity of its output shaft.

A joule is equal to one Newton-meter, which is the amount of work needed to move a 1 Newton force a distance of 1 meter. When you divide work by time, you get power, measured in units of joules per second. This is also called a Watt. 1 Watt = 1 Joule Sec. This is the formula to calculate output power.