The table below shows you consumption currents on different rails in all the mentioned tests. Just to remind you: the +12V1 line corresponds to the mainboard, graphics card and hard disk drive, and the +12V2 line to the processor.

It is already clear that the computer mostly loads the +12V rail. The currents on the +5V and +3.3V rails are too low in comparison with the load capacity of these lines (they are 25 and 20 amperes, respectively, even for a weak 250W ATX12V 1.2 power supply). As you may remember, it was high loads on the +3.3V rail that made the developers of the ATX standard introduce this power source into the power supply. Earlier, in the AT standard, this voltage had been generated right on the mainboard out of +5V. The load capacity of the +3.3V rail was growing steadily for the first four years of the existence of the ATX standard, reaching a maximum of 28 amperes (for a 300W unit), and special attention was given to the stability of this voltage (the standard described compensation of a voltage drop under loads only for this power rail).

But today it seems like we can soon abandon the +3.3V line altogether. The Athlon 64 mainboard still consumes a little power from this line, but the consumption of the LGA775 mainboard is negligible, being less than 3 watts.

It’s similar with the +5V rail: there was a time when it used to bear the main load and top-end power supplies allowed a current of up to 40-50 amperes on it, but now the load on the +5V line is less than 5 amperes. Well, this passing away of the low-voltage power lines is quite logical: consumed power being the same, consumption current is lower if voltage is higher. If modern processors and graphics cards were powered via the +5V or, worse yet, +3.3V rail, the number of wires in the power connectors would have to be doubled.

For better readability, I drew diagrams of the consumed power (not of the currents, as in the table above). The diagrams are drawn in the same scale, so you can compare the two computers.

Besides the obvious and repeatedly voiced statement that the Athlon 64 generates less heat than the Pentium 4, the diagrams also make the difference between the consumption on the +12V rail and on the +3.3 with +5V rails stand out. If you summed up 12V1 and 12V2 in one column (these rails are actually a single source inside the power supply), the columns of the low-voltage rails would be just lost in comparison.

These tests done, we can get closer to FSP’s power supply.