As in the exact components in your existing machine? I suggest you use the device specifications to calculate this instead of measuring it. Components won't always output their maximum power requirement and unless if u want to sit infront of ur computer looking at the measurements, I suggest u just read the spec.
Also, devices won't use their max power consumption simultaneously. A good rule of thumb is to use a PSU calculator with ur exact components or just add up the #'s manually based on "official" data, and make ur PSU power higher than this. b/c ur final # will be the max power requirement. It will hardly reach this during ur use.