Silverstone Zeus ST85ZF 850W Power Supply Review

Cases & PSU/Power Supplies by KeithSuppe @ 2007-01-11

Silverstone Technology Ltd. is a relative newcomer to the PC-world having been founded in 2003. As a manufacturer of power supplies, CPU-coolers and enclosures they aggressively sought to compete with the very best in these product categories. Over the last year they have come into their own with the release of the well received Temjin TJ06 aluminum case and Zeus line of PSUs. Silverstone is now a relatively familiar name and we have the flagship of the Zeus series, the ST85ZF.

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Connectors and Cooling

ST85ZF Connectors

Madshrimps (c)

Silverstone Zeus ST85ZF Connector Source Rails
24-Pin Motherboard Connector +3.3V, +5VDC, +12V3
EPS 12V 8-pin Connector +12V1, +12V2
EPS 12V 6-pin AUX Connector +3.3V, +12V3
PCI Express 6-pin Connector #1 +12V4
PCI Express 6-pin Connector #2 +12V4
PCI Express 6-pin Connector #3 +12V2
PCI Express 6-pin Connector #4 +12V3
Molex Connectors 4-pin (x6 HDD) +5VDC, +12V3
Floppy Connectors 4-pin (x2 FDD) +5VDC, +12V3
SATA Connectors (x6) +3.3V, +5VDC, +12V2

The Zeus ST85ZF offers a total of four PCI Express 6-pin connectors and a fifth 6-pin connector Silverstone describes as a 12V EPS "AUX" 6-pin. Each PCI Express 6-pin connector is clearly labeled and reading Silverstone’s online manual (.PDF) will aid you in choosing proper loading among PCIe connectors, especially when running a SLI configuration: With dual NVIDIA Geforce 7950GTX cards, please use the following combination of PCI-E connectors only:

  • PCI-E 1 & PCI-E 2
  • PCI-E 1 & PCI-E 3
  • PCI-E 2 & PCI-E 3

  • Madshrimps (c)

    At 850W and a total of 1050W peak I was relieved Silverstone doesn't try to be all things to all people incorporating modular connectors into the mix. As I've stated repeatedly modular connectors introduce resistance at the connection points where oxidation will occur and the introduction of an additional daughter-board PCB from which wiring travels from the main board to this board and voltage is distributed along traces. In the thumbnail below we see all five 6-pin connectors including the 6-pin 12V EPS connector, with +3.3V assigned to pins 1,2 +12V3 assigned to pins 3,6, and GND assigned to pins 4,5.

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    The 24-pin motherboard connector and 8-pin baseboard (CPU) connector (also includes an 8 to 4-pin baseboard adapter). I find an 8 to 4-pin adapter preferable over a model which attempts "lock" two 4-pin connectors since they can easily dislodge if not held properly when plugging into the CPU power connector. For the uninitiated this can present some problems. Of course with a 8-pin to 4-pin adapter the rails which may be separated are now combined increasing current to the processor, which will benefit those running Intel Presler or Cedar Mill core CPUs.

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    Thumbnails below exemplify the remainder of the connectors. This includes: 6 x SATA divided among two cables ( three per cable), 6 x Molex divided among three cables, two of which also feature a single floppy connector for a total of 4 x HDD, 2 x FDD and a third cable with 2 x 4-pin Molex (HDD, AUX etc).

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    Cooling is critical on any power supply, unfortunately the ATX standard uses (abuses) the Power Supply as an additional exhaust point in the case. This has affected the power supply industry for years elevating the temps at which they must perform. Power Supply makers whom do not take this under consideration, do so at their own peril. Silverstone's Zeus ST85ZF features a full mesh front panel where a large volume of air can flow freely into the unit.

    Madshrimps (c)

    Silverstone (Etasis) chose a Sanyo Denki 80mm fan to cool the ST85Zf. Finding the exact part number (9A0812S413) on the Sanyo Denki site was fruitless since it's been replaced with 9A0812S4021. This standard model moves 42.2CFM @ 12V for 34dB(A) with an operating range between 6 ~ 13.8V. Sanyo Denki does offer thermally controlled fans, however; this is a standard model, Silverstone chose their own thermistor activated rheostat which allow placement of that device where it does the most good.

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    The photo in our next section should exemplify the cooling advantages of a dual PCB design. With components divided across two PCBs and then inverted, in theory many more devices are exposed to the airflow. In a standard design larger components nearest the exhaust fan can obstruct airflow and increase noise. Silverstone also chose to place the fan inside the case, which may provide better cooling, but certainly reduces noise.

    In all high-current PSU reviews I make note of the power cord's wire gauge supplied by the manufacturer. As we surpass the 1KW touchstone in the PSU world, wire gauge (see Powerstream - AWG chart/calculator) plays a substantial role. While our ST85ZF is rated at 850W it has a Peak rating just under 1KW. Few reviews bother to mention power cord AWG thickness. This may be due in part to the average house-hold current limit which is usually 15A, although has little to do with the fact a thicker cord will still improve current draw. The problem for the manufacturer is, as usual cost, with 12AWG or 14AWG wire costing over twice as much as 18AWG. Silverstone includes a 16AWG power cord, a choice which keeps cost low and performance high (below).

    Madshrimps (c)

    Onto the internal layout -->
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    Comment from Sidney @ 2007/01/11
    From Hardware Secrets; Why 99% of Power Supply Reviews Are Wrong. I'm sure that article will have a substantial impact on most PSU reviews you have read.
    I've read the article the day it came out, and found the statement rather inaccurate. A Chroma station, measuring amp and or wattage or voltage by replicating the manufacturer QC station process, and even taking IQC (incoming QC on purchased components) are for the engineering professional in electrical field. When I test drive a car, I only need to know how it responses, sitting/driving position, steering inputs, acceleration (if it is important to me), gas mileage (if it is labled for good mileage consumption), price point and the "look", etc, etc ...... One thing I don't mind not knowing is all the engine, chassis, suspension, gear-box design and specifications (although some of us do want to know because we are very good at it).

    99% of reviews are wrong sounded is a bit odd. It depends on the type of audience; 99% are electrical engineers (by formal training or otherwise) and PC enthusiasts; leaving 1% reader who asks that give me a power supply that fits well in my case and support my system without over kill in paying for something I don't need is a strange statement.

    By the way, the article serves me well
    Comment from EsaT @ 2007/01/19
    I just checked article more closely and I think you are wrong about 12V rails being really separate.

    Basing to these pics looks much like at least 1 and 2 are "jumpered" (those thick metal jumpers) from same trace.
    And basing to bottom side of PCB also 3 and 4 are propably similarly connected.

    In fact looks like all 12V rails are directly connected to each other after those "jumpers", PCB traces seem to connect to each others on left edge of pic.

    Originally Posted by lazyman View Post
    When I test drive a car, I only need to know how it responses...

    99% of reviews are wrong sounded is a bit odd.
    So you test drive car using just gear 1?
    Or more precisely without any driving and seeing just that engine works at idle?
    Comment from jmke @ 2007/01/19
    rather testing driving the car on race roads, normal roads, traffic jams, long distances, short distances, parking, booth space, easy maintenance, wheel removal kit, seat arrangements, mirror placement, etc etc

    you don't need to know how the engine works to make an evaluation of how the car drives

    knowing how the engine works can help to explain why the car drives as it does, but it's not a necessary ingredient to make a good evaluation of the car, of course, cars and PSU are not quite a like, and comparo here might not be appropriate
    Comment from Sidney @ 2007/01/19
    If it is automatic trans; most people don't just put it in "D"; drive away
    If it is humming along quietly, most drivers don't care how it works
    I am referring to majority of drivers.
    Comment from EsaT @ 2007/01/19
    Originally Posted by lazyman View Post
    I am referring to majority of drivers.
    But most people propably wouldn't trust test drive of car done by using only gear 1, that's what that majority of PSU reviews with barely 1/3 of load specified in ads of PSU are...

    On the other hand this specie might have once again digged deeper than previously reached level of rock bottom.
    Comment from Sidney @ 2007/01/20
    You don't buy a car just by reading test report I hope
    Comment from jmke @ 2007/01/20
    it does help make the decision a lot, testing driving PSU is hard
    Comment from Sidney @ 2007/01/20
    My initial post was related to the 99% reviews being wrong. Here is my take-
    1) A car is rated to have 500HP rear or front wheel power; top speed 180MPH. There will be manufacturing variables, and a dyno test may or may not prove 100% accurate. Now comes the 180mph test, again there are many variables plus having a track to do the test against normal traffic. A test drive reviewed at 120 MPH without the track to top out is not 100% wrong. It merely ran out of track on this part of the review.
    2) Since PSU is not regulated by any government (unlike cars) rating except UL for safety. It is highly dependable on the manufacturer's ablility to hold certain professional standards such as ISO which I strongly recommend consumers to look into.
    3) The use of any test equipment not regularly certified does not mean much to me.

    Lastly, PSU tested even at 100% spec on bench using Chroma station at a given time does not gurantee real life performance against weather condition and irregular or variable input voltage (from the wall or motherboard). Look for solid and reputable manufacturer or name brand; reading test reports include cable length, flexibility, size to fit most or just certain cases, and noise level; to say 99% of reviews are wrong because they might not test the max output is "odd".

    We could go another step to look into component specs +/- 3%? Or requesting BOM (bills of material) and supplier listings?
    Comment from Liquid3D @ 2007/01/25
    I actually re-evaluatewd that article myself. I also found several points which were inconsistent. I wasn't trying so much to discredit our or any other methodologies as I was trying to challange those sites whom feel their tests are beyond reproach. Many of the top test sites with the very best hardware use voltage regulation as a standard test.

    When you think of it, since all PSU's have voltage regulation it's not as if their testing the PSU's "power reserve" their actually measuring (if it's possible) the unit's ability to compensate for Rail fluctuation. Without "true" independent voltage regulation fluctuation will be regulated, often at the xpense of theo others Rails. Therefore measuring rail stability may only show one or two phenomenon: First - time it takes to compensate (get the rail back to "spec". Second - wether or not PSU is able to compensate without any affecting other rails or circuits in the design. The paper states the latter is almost impossible because one would need to monitor all rails simultaneously.

    IMHO it's not so much the rail in question is immedately regulated, but more importantly this regulation is proprietary as is the current source behind it.

    For exmaple if 12V3 dips and it is compensated for, does this now effect 12V1, 12V2 and 12V4? While independent voltage regulation may avoid any impact on other rails, much more important to me is where that power comes from?

    The jumpers you refer do not seem to connect any of the 12V rails on the face of it, but I'll follow the traces to be sure if you like?