Buying advice PC power supplies - How to save money

Although little attention is paid to the PC power supply, it is actually extremely sophisticated. Finally, when the load is heavily changing, it must have clean DC voltages. Up to the two-digit amperes range, and should still be cost-effective, compact, quiet and effective. Especially the latter has become more and more important for marketing purposes.


For example, the "80 Plus" certification has been in place since 2004, which is intended to guarantee that a power supply between 20 and 100 percent load achieves an efficiency of at least 80 percent. In the meantime, the additions of bronze, silver, gold and platinum are even more demanding (see table).


First of all, this development is of course welcome. More efficiency in the power supply not only results in lower power consumption, but also ensures less waste heat, which sometimes has to be eliminated by means of air conditioning with high energy consumption. If less waste heat is present, it is considerably easier to keep the power supply from heat-collapsing even without a loud fan.


In a computer whose components (mainboard, CPU, graphics card, memory, hard drive) are recording 300 watts, a power supply with a 65 percent efficiency drops 161 watts of lost power in the form of heat. Anyone who has already approached a luminous 150 watt light bulb can get an approximate picture of the resulting waste heat.


With a power supply with 80 percent efficiency, only 75 watts - not even half - would drop. With an "80 Plus Platinum" certified power supply, it should be even more ludicrous 19 watts. No wonder that the 80-plus power supplies, which have been tormented at the end of our network test, still have a lukewarm breeze despite high power and the slow-rotating fans are hardly perceptible

Miracles, however, should not be expected from the savings potential. In our first scenario - that is, two hours of daily operation at 20 cents per kWh - a power supply with an 80 percent efficiency compared to a 65 percent with an assumed 100 Watt net consumption of the computer components saves just 4.21 Euro per year

If the components would average an average of 300 watts, e.g. With a high-end game PC, could save 12.63 euros per year. A Bürernchner operating 8 hours per day, 200 days per year, would reach 49.23 euros at 65 percent and 40 euros at 80 percent efficiency of the power supply, assuming a net output of 100 watts. Nevertheless, the savings potential should suffice to justify the additional costs of a non-certified power supply.


Whether the exchange of a power supply is worthwhile, is questionable. However, the replacement of an old, inefficient power supply with a new one could well be expected for computers running 24/7 operation all year around the clock. If you turn 100 watts of net power again, you could save on an exchange with a power supply with 65 per cent efficiency against one with 80 per cent already over 50 Euro per anno. An 80 Plus certified 450 Watt power supply should always be available for the amount.