Testing

To test the power supply unit, we will not connect it to an everyday system as we would be unable to know the exact load that we would provide and wouldn’t be able to vary the load. Instead we will use power resistors which are nothing more than normal resistors but capable of consuming a good amount of power. How much power depends on the resistance and capability of the resistor, and can be easily calculated by Ohm’s law (Amperes = Voltage / Resistance, Power = Voltage * Amperage).

Hence for example a 1Ohm resistor attached to the 3.3V line will allow 3.3A through it and consume about 10W of power. When adding two of these resistors in parallel, you double the power consumption and allow 20W to be consumed as you halve the resistance this way. Adding more will increase the power consumption. Of course that is not entirely accurate on paper as the fault tolerance of these resistors is high and almost none are exact to their resistance specifications, but after using them we could calculate how much power each bunch of them would consume accurately. This way we can add fake load to any power supply unit, and on any power line we wish with good accuracy.

For testing the Be-Quiet StraightPower 600W unit, taking into account the design and their power specifications, we took the following steps:

StraightPower 600W
Total Load	3.3V Load	5V Load	12V1 Load	12V2 Load
25% (~160W)	8A (26.5W)	10A (50W)	4A (48W)	3A (36W)
50% (~300W)	20A (66W)	16A (80W)	7A (84W)	6A (72W)
75% (~450W)	20A (66W)	20A (100W)	10A (120W)	14A (168W)
100% (~600W)	28A (90W)	25A (125W)	16A (192W)	16A (192W)

The room temperature when the test took place was 27 Celsius degrees. Despite the 4 separate 12V lines of the StraightPower unit, we decided to use only two of the lines, one from the ATX cable and another from two Molex connectors. The 600W had surprisingly strong regulation and could withstand exactly 600W of continuous load without any issues, although it was rather noisy when loaded so much. We tried loading the unit further, but even if we add only 10W of load, the unit shut down quickly. There is probably some kind of overload protection integrated in the StraightPower units.

For testing the Be-Quiet StraightPower 650W unit, taking into account the design and their power specifications, we took the following steps:

StraightPower 650W
Total Load	3.3V Load	5V Load	12V1 Load	12V2 Load
25% (~160W)	8A (26.5W)	10A (50W)	4A (48W)	3A (36W)
50% (~300W)	20A (66W)	20A (100W)	7A (84W)	6A (72W)
75% (~485W)	30A (100W)	20A (100W)	12A (144W)	12A (144W)
100% (~640W)	30A (100W)	30A (150W)	16A (192W)	16A (192W)

dont have flash installed? then click here for a jpeg

The room temperature when the test took place was 27 Celsius degrees. Despite the 4 separate 12V lines of the StraightPower unit, we decided to use only two of the lines, one from the ATX cable and another from two Molex connectors. The 650W had slightly overvolted 12V lines right out of the box, which is not bad at all. Actually seasoned overclockers would say that this is a very good thing. There are fluctuations, mainly on the 12V lines at maximum load, but nothing important enough to begin worrying about.