No power, no dice: it's really that simple. All components in a PC system need electricity, and ever-increasing amounts of it, so the power supply has to come up with the goods. Manufacturers can claim what they like, but the claims don't always translate into reality, and very few users have a good idea about the power drawn by the individual components.

This is why we test power supplies ourselves. To help you understand the procedure we use, we will now shed some light on the issues involved, and explain our testing procedure.

Performance

Performance is always at the top of the list of a power supply's features, but the trick is to find out the device's actual power output, and whether voltages lie within the specified values. Voltage tolerances at all load levels are described in the ATX12V Power Supply Design Guide. This document is the technical basis for all power supplies, and the standards it contains are used for all our measurements.

THG's power supply test platform in action

We employ a special platform to test loads on power supplies. At its core are four electronic high-performance loads, each of which can handle a maximum current of 50 amperes. This setup enables us to record measurements extremely accurately. Conventional adjustable resistors are used for the standby voltage and the rarely used -12V and -5V paths. A network filter ensures that any interference pulses from the network do not distort our measurements.