The new top processors from AMD and Intel continue to raise the bar for power needs of PCs: a CPU alone sucks nearly 90 Watts. The new graphics cards also place high demands on power. Requiring up to 70 Watts in 3D mode, the GeForce FX 5800 Ultra Accelerator is not far behind the processor in power consumption requirements.

A reliable, potent power supply is required to prevent instability and system crashes. THG took a close look at 13 power supplies rated higher than 400 Watts. The test showed that lines supplying the system with +3.3, +5 and +12 Volt lines generated, on average, 20 Watts less overall power than was promised by the product name or product branding.

Is It Just Marketing, Or What?

The highest power rating, 520 Watts, is boasted by the Topower Top-520 MP. Upon closer inspection of the label, however, you'll find that the combined output of the +3.3, +5 and +12 V lines is limited to 500 Watts. The remaining power is provided by the standby line and the -5 and -12-Volt lines are no longer needed by most systems. With output maxing out at 472 Watts, the Top-520MP finished behind the leader, the Antec True 480P, at 484 Watts. Fortron Source's FSP400-60PFN leads the 400- to 449-Watt class with 452 Watts.

It's important to note that the maximum power measured, which can also exceed the manufacturer's specifications, is an indication of the performance and quality of the components. Because of the danger of overheating and the necessity to stay in compliance with the manufacturer's guidelines so as not to void the warranty terms, the top power rating cited by the manufacturer should be adhered to in continuous operation. Enermax, for example, rates overall output for its EG465AX-VE(W) FMAX at 460 Watts. The lines with positive Voltage for the PC components are limited to a lowly 432 Watts. All in all, the Enermax device has a maximum output of 439 Watts.