Overclock3D.Net :: Print Page :: Silverstone Zeus 850w ST85ZF Quad SLI PSU

Silverstone have updated their packaging slightly with the inclusion of ROHS stamp which came into force on the 1st July 2006. We can also see that the front and top of the packaging offer some basic specifications along with some images of the unit and the rated output of the units rails.

Turn the box around to the side, and we can see some of the 'Special Features' of the Silverstone unit. The ST85ZF boasts 6 SATA connectors, 4 PCI-E connectors, a maximum efficiency of 87% and multiple over-load/volt protection features.

A handy feature of the packaging is the plastic handle on the top of the box, which will certainly make carrying this unit home from the shops a much easier task.

Included in the package are the following items:

- 1x 8-Pin AUX to 4-Pin P4-12v Adapter
- 1x Power cable
- 1x ST85ZF Manual
- 4x ATX Screws
- 1x Silverstone ST85ZF PSU

The unit itself is sandwiched in-between two cardboard layers, each padded out with Styrofoam shapes to protect all corners of the PSU. Also included is a small cardboard box containing the power cord, screws, 8-pin and 4-pin P4-12v converter. The bundle of cables are contained within a bubble-wrap sleeve and tied together with a large cable-tie.

Having a quick flick through the ST85ZF manual I can see that Silverstone have provided detailed information regarding the +12v rail layout of the unit. However, there's an easier way to find out this information, which can be seen on the 'Connectors' page.

Silverstone seem to have a tradition of keeping their power supplies very plain, and only spraying them in matt black paint. This is certainly true of the ST85ZF which is very similar in appearance to the ST75ZF.

The back of the power supply has the usual mesh grill, which allows for the air pushed over components by the 80mm fan to exit the back of your PC case. Also included is an LED which shows you the current status of the unit. When switching the Power Supply on the LED turns from Red to Green. Only when the LED is Green is DC power supplied to the rails.

It's good to see that Silverstone have opted for a black fan grill on the front of the unit, as the silver one used on the ST75ZF looked somewhat out of place.

The sides of the unit have also been kept very simple, with only a specification sticker containing the usual warnings and information about the power supply, along with its rated output for all of the rails.

The Zeus comes complete with a big bundle of cables, all wrapped together inside a bubble wrap bag and secured with a cable tie.

The Molex and SATA connectors have been sleeved up to the first connector, which is an improvement over the ST75ZF that left these cables unsleeved. It would have been nice for all cabes to be completely sleeved, but this would serve no practical purpose other than looks.

The overal quality of the sleeving job is excellent, using both cable ties and heat shrink to hold the sleeving in place.

Credit has to be given to Silverstone for labelling all connectors with the corresponding rail that they obtain their +12v power from. As we can see from above, the Molex connectors obtain their 12v power from the +12v3 rail, and one of the PCI-E connectors obtains its power from +12v4.

This is especially helpful for ensuring that you distribute the load used by your components amongst the 4 available +12v rails.

The ATX Connector is native 24-pin. Unlike other power supplies, it doesn't have a 4-pin block which can be snapped off for backwards compatibility with older motherboards. Users of the older 20-Pin ATX motherboards will have to purchase a converter in order to use this power supply.

The ST85ZF is also native EPS-12v, providing the user with an 8-Pin connector. However, Silverstone have included an extension cable, which coverts the connector to 4-Pin ATX-12v.

The ST85ZF utilises 2 circuit boards placed at the top and bottom of the casing in order to fit all of the components inside the unit.

We can see from above the internals of the ST85ZF are manufactured by Etasis, a well respected industrial power supply manufacturer. Those of us 'on the ball' will also notice that the circuit board used in this power supply is exactly the same model as that used in the 750w ST75ZF version.

So what makes the ST85ZF 850w if it has the same circuit boards as the 750w ST75ZF model? Well basically, upgraded components...

As you can see above many of the components placed inside the unit are labelled EPAP-850. These components are what gives the unit the extra 100w advantage over its brother the ST75ZF.

Above we can see what appears to be an adjustable potentiometer (pot). ~~This will most likely be responsible for adjusting the voltages on the rails of the unit and can be helpful when voltage levels fall outside of ATX specifications.~~ Unfortunately I was unable to test whether this pot made any difference to the voltages, as the ST85ZF is far too awkward to disassemble and reassemble.

EDIT 01/08: Silverstone have informed us that this potentiometer is not responsible for adjusting the voltages. All voltages are set at the factory and should not need adjusting.

Cooling the Zeus is an 80mm fan manufactured by Sanyo Denki. The San Cooler 80 is able to push a total of 42cfm when running at 12v, with a noise output level of 34dBA.

The ST85ZF has some of the most stable +3.3v and +5v rails we've ever tested at OC3D to date. With little to no fluctuation, this brings the ST85ZF in direct competition with the recently reviewed PC Power & Cooling 1kw PSU.

Continuing the trend on the +12v rails, the ST85ZF breezes through our stress testing with a maximum of 0.4% fluctuation on the rails. Yet again, these results place the ST85ZF up against some of the best power supplies we've ever tester here at Overclock3D.

Efficiency Testing

Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains against the power (in watts) consumed by the OC3D power supply stress tester.

The results may not be as accurate as those produced by professional testing equipment, but will certainly come in handy when comparing several power supplies against each other.

The Silverstone Zeus 850w was placed under a load of 646 watts. This counts for a total of 76% of the power supplies rated output. At this load, the power supply required 786 watts from the mains to produce the 646 watts required by our custom made power supply tester.

Therefore the efficiency of this power supply can be found by a simple equation: (646 / 786) * 100 that works out to be an efficiency rating of 82.1%.

Noise Testing

At present Overclock3D doesn't have the professional equipment required to reliably measure the noise output of devices. However, as a new part of our testing procedure we will be recording the PSU at idle and load so that you can make your own judgments. All recordings are taken at 30cm distance from the unit.

Idle Recording - Download
Load Recording - Download

As previously stated, the ST85ZF utilises a Sanyo Denki San Cooler 80mm fan, which pushes a 42cfm at 34dBA when running at full speed. Thankfully Silverstone have implemented a fan speed controller that adjusts the RPM based on the temperature of the unit.

Under idle conditions the fan speed was significantly throttled. This meant that all that could be heard was the whisper of air moving around the unit. With the ST85ZF installed inside a case, I was unable to hear the unit at all.

When placed under load, the ST85ZF gradually increased the fan speed to counteract the heat. As you can hear from the recording above, the ST85ZF was quite noisy. However, with the ST85ZF installed inside a case, the noise levels were much more reasonable.