X-bit labs

ATX Power Supply Units Roundup. Part IX (page 13)

Category: Other

by Oleg Artamonov

[ 03/28/2008 | 02:47 PM ]

The PSU is equipped with the following cables and connectors:

• Mainboard cable with a 20+4-pin connector (47cm)
• CPU cable with a 4+4-pin connector (51cm)
• Two graphics card cables with one 6+2-pin connector on each (50cm)
• One cable with three Molex connectors (50+15+15cm)
• One cable with three SATA power connectors (50+15+15cm)
• Two connectors for graphics card cables
• Three connectors for power cables of PATA drives
• Three connectors for power cables of SATA drives

Included with the PSU are:

• Two graphics card cables with one 6-pin connector on each (50cm)
• Two cables with two Molex connectors and one floppy-drive plug on each (50+15+15cm)
• One cable with three Molex connectors (50+15+15cm)
• Three cables with three SATA power plugs on each (50+15+15cm)

A splitter from one Molex to two fan connectors (a +12V and a +5V one) is included with the PSU.

Together with an APC SmartUPS SC 620 this power supply worked at loads up to 366W (from the mains) and 315W (from the batteries). The switching to the batteries was performed without problems.

The PSU passed the full-load test easily.

The output voltage ripple at full load is within the normal range.

Like most PSUs with dedicated voltage regulation, the ZM850-HP draws a cross-load diagram with a lot of green. The +12V voltage barely deflects more than 1% from the nominal value. The +5 and +3.3V voltages are less stable, yet it is only at nearly extreme loads that they deflect much from the nominal values.

The fan was rotating at a constant speed of 720-730rpm at loads up to 700W! That’s a record-breaking performance. I even got some apprehensions during the test about whether it worked at all. It’s only when the load was nearly maximum that the speed began to grow up. As a result, the PSU is not just quiet. It is silent. You can’t hear the fan at such a low speed unless you put your ear right next to it.

The tradeoff of the quiet operation is high temperature, of course. There was a 20°C difference between the air temperature at the input and output of the PSU. It’s hard to tell how this high temperature can affect the reliability of the PSU especially as its internal space heats up less than with the classic component layout because the heatsink has been moved to the external panel of the case.

The PSU is 87% efficient at a load of 350W. Then it lowered somewhat, yet remained above 80% all the time. The power factor was 0.98-0.99 through a wide range of loads.

Well, Zalman’s decision to cooperate with Enhance instead of FSP Group can now be understood. FSP’s models have provoked some questions recently (see this review for details) whereas the ZM850-HP makes a very positive impression with its good electric parameters as well as quietest work. It has rather large dimensions but users whose PC really needs an 850W power supply surely don’t use cramped system cases.