X-bit labs

ATX Power Supply Units Roundup: 9 Powerful Models Tested (page 17)

Category: Other

by Oleg Artamonov

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

A maximum load of 34A is declared for the +12V rail and it is not divided into two 18A channels. As I’ve written in my reviews, this division is made only to comply with the EN-60950 safety regulation and does not affect the voltage stability or any other of the PSU’s characteristics (many manufacturers claim that two +12V channels ensure a higher load capacity or a higher stability of the voltages, but this is not true).

Curiously enough, the PSU label only mentions one input voltage (115V/60Hz). In fact, it has an ordinary 115/230V switch and, like all switching power supplies, is indifferent as to 50Hz or 60Hz is the mains frequency.

There are two stationary cables:

• Mainboard power cable with a 24-pin connector (with a detachable 4-pin part), 47cm long
• CPU power cable with a 4-pin connector, 53cm long

And these cables are also included with the PSU:

• One cable with three Molex connectors (46cm to the first connector and 15cm more to each next connector)
• One cable with three Molex connectors and one floppy mini-plug (46cm to the first connector and 15cm more to each next connector)
• Two cables with three SATA power connectors (46cm to the first connector and 15cm to each next one)
• Two cables with 6-pin graphics card connectors, 45cm long

The cross-load characteristic of the PSU isn’t really good. All the three voltages exhibit but poor stability, the +12V even going through all the range from the minimum to the maximum. The PSU allows easily getting the declared power, but it is not good from the standpoint of modern, +12V-oriented PC systems that the whole cross-load characteristic is shifted up and leftwards into high +5V loads whereas in the bottom right part of the diagram (where there are high loads on the +12V rail) the voltages are out of the acceptable limits.

The voltage ripple under 450W load is 35 millivolts on the +5V rail (most of this ripple is 100Hz low-frequency pulsation, high-frequency pulsation accounting for only 10 millivolts); 62 millivolts on the +12V rail (high-frequency pulsation accounting for only 14 millivolts) and 30 millivolts on the +3.3V rail (high- and low-frequency pulsation each accounting for half that value).

The cooling system this PSU is equipped with is rather strange and I have only seen it in PSUs manufactured by Wintech: one 120mm fan and one smaller fan. In PSUs from other manufacturers there are either two small fans (80mm or 92mm) or a single 120mm fan.

The graph shows the speed of the two fans when the manual controller is set to the minimum position. As you see, the speed depends but slightly on the PSU load, like with the above-described MGE Vigor 500. When the manual controller is set for the maximum speed, the speed doesn’t depend on the load at all and is 3300rpm for the 80mm fan and 2030rpm for the 120mm fan. This speed management can hardly be considered right because the PSU may overheat under high loads when the speed is manually set to the minimum. At the maximum fan speed the PSU is too noisy even at low loads.

The efficiency is quite good at average loads, but degenerates considerably at high ones. The power factor is normal for a PFC-less model.

The SinTek WIN550XSPX-X is neatly assembled and has good parameters, yet I would want to have more stable voltages, especially on the +12V rail, and a more efficient fan speed management system that would adapt for different loads without the user’s intervention.