Our attempt to test the Noise Magic power supply had disastrous consequences. This is a modified Enermax unit fitted with a Papst fan. It stopped working after one minute. When we tried to switch it back on again after a suitable delay, it simply burned out. The Maxtron TOP-520P4 and the PCW Whisper Power "gave up the ghost" with a loud bang!, well below their rated output. We were unable to revive them from the dead, because their electronics were damaged in the process. Overly-optimistic output figures from Maxtron - this 520-watt rated power supply could only deliver a maximum 446 watts in our tests! At 304 watts, the PCW Whisper Power was 10% short of its manufacturer's rating. These three test candidates with burned-out electronics were not evaluated.
More Power Than Specified - Fortron FSP, Verax And TSP
The Verax FSP300-60ATV and Conrad FSP350-60BTP models are a good choice for overclockers, since they measured up well and provided a reasonable amount of power in reserve. Both power supplies are stable in use at their specified maximum load. That's not all: both the Verax 300-watt model and the 350-watt Fortron FSP model switch off when they reach 30% overload, which is a definite plus. Power supplies should switch off when they overheat due to overload, to prevent damage to other hardware components. This feature also lets the user know there is a problem, so that it can be traced and, hopefully, fixed before there is a disastrous failure.
Another recommended unit is the HEC-300LR-PT from Herolchi. Although rated at 300 watts, this unit actually delivered a maximum of 350 watts, and thus provides adequate power reserves. It is also fitted with an automatic cutout. In view of its good performance, its retail price of about $50 is very reasonable.
Of all models tested, the TSP TSP-420 P4 had the highest measured output. Rated at 420 watts, it actually delivered 497 watts.
Conflict Of Interests - Low Noise Vs. High Output
A power supply that produces lots of power unfortunately also generates a high amount of heat. Most manufacturers specify a nominal operating temperature of about 50 degrees Celsius. Fans are used to ensure adequate air circulation and cooling. However, as with CPU coolers, power supply fans can be an irritating source of noise. Manufacturers are now aware of this noise factor and use a variety of methods to keep noise levels down to an acceptable level.
Engelking Elektronik offers the best solution. As well as a fan, the AP2-6300SFC-A is fitted with a passive heat sink at the back. Engelking says that its product will operate at up to 49 degrees Celsius without the fan, and we can vouch for that. The power supply worked totally noise free under full load over an extended testing period. The unit was still surprisingly quiet, even when the fan was running. This achievement puts the Engelking in top place for ergonomics. On the other hand, its asking price is around $235, which is a bit steep.
The Verax power supply, our runner-up in the ergonomic stakes, takes a different approach. Verax fitted this modified Fortron-source power supply with a special fan, which remains very quiet as long as it is running slowly. Other power supplies in the test, however, generated noise levels above the 50 dB mark, including the Coba, Channel Well, Leadman and Task. In our opinion, loud humming, loud vibration and/or high-pitched whistling are the results of poor product design. And, as far as we are concerned, this poor design is directly traceable to manufacturers' excessive cost cutting at the production stage.