What is the maximum safe current for Mac Pro PSU?
Not all of the listed items have a voltage of 12 V. E.g the HDD+ODD has only 5 V and the CPUs have a much lower voltage. According to Intel the voltage of the Xeon® Processor X5670 maxes out at 1.350 V and the TDP is 2 x 95 W (and not 2 x 12 V x ~46 A = 1104 W).

So just adding all currents and multiplying them with 12 to get the wattage is not appropriate here.