This is one of the best psu calculators i've seen....
One Question: How do you measure the actual currents on 12V rails once your PSU is working in your PC...Are there any software tools, or something else?
Dont try measuring current on the DC line with those cheap multimeters. Most support max 10amps measurement for DC and you will end up blowing the multimeter if you try to measure dc amps as its way higher than 10 amps on an modern pc.