X-bit labs

ATX Power Supply Units Roundup: 9 Powerful Models Tested (page 11)

Category: Other

by Oleg Artamonov

[ 02/28/2006 | 10:46 PM ]

And the last touch, the developers decided to use individual colors for each contact of a connector. In other PSUs, all +12V wires are colored yellow, +5V are red, “ground” are black, etc., but here you just can’t find two same-color wires. There are some twenty pins in the mainboard power connector, and wires of twenty different colors go to it. I can’t find any practical sense in such decorations and this may make it difficult to repair and diagnose the power supply for failures. This is also simply confusing: a CPU power connector with a red wire may perplex any advanced user because red denotes +5V in other PSUs and this voltage is not supplied to the CPU connector.

As mentioned above, the PSU’s label promises a maximum output power of 400W. The PSU complies with the ATX12V 2.0 standard, meaning that the load power on the +12V rail is two times higher than the load on the +5V and +3.3V rails.

The cross-load characteristic of the PSU is surprisingly good. It works without problems across the entire range of allowable loads. The +3.3V voltage is not very stable, yet it never violates the required limits.

At a load of 385W, the voltage ripple on the PSU’s output is 16 millivolts on the +5V rail, 15 millivolts on the +12V rail and 14 millivolts on the +3.3V rail. The pulsations are all high-frequency ones, without a 100Hz constituent.

It is next to impossible to measure the rotation speed of the fan in the Magnum 500, so the diagram above shows you the dependence of the fan voltage on the PSU load. The diagram shows that the voltage grows up linearly along with the load (along with the PSU temperature, to be exact). The noise from the fan is perceptible at loads higher than 300W.

The efficiency and power factors of this PSU are not very low, but are definitely worse than those of the Enermax and FSP models (see above). This PSU just fits the requirements of the standard (an efficiency of no less than 60% at a load of 100W and no less than 70% at a load of 200W and higher).

My overall impression about the Magnum 500 is rather negative. Yes, the technical parameters of this PSU are good s it yields stable voltages with a low voltage ripple, but some design solutions employed in it are rather questionable. It has two supposedly diagnostic devices (an LCD display and a row of LEDs), one of which is absolutely useless and another would have been better replaced with vent holes. Its ventilation was not well thought-out. The shabby-looking cables with their insanely excessive screening are not very easy to deal with, too.