Seventeam 850watt Modular

Looking for a PSU that is multi railed, but that does not have a gazillion rails? Today are we going to look at a PSU from Seventeam that is a multi rail, but it only has 2 rails.


PSU’s (or Power Supply Units), are some of the most misunderstood components in our entire computer. When we go looking for a new PSU, we normally end up grabbing the cheapest one we can find and what video card manufacturers recommend (in their list of approved PSU’s), not really taking into account the multiple variables we might need to consider when purchasing a PSU.

In today’s market, PSU’s have multiple rails (two or more 12 volt lines) or single rail (one 12 volt line) to add to an already confused consumer and/or market. When multi railed PSU’s first came out, the concept of the type was perfect, take one large 12 volt rail, split it into a couple of different 12 volt rails, thereby increasing the efficiency and stabilizing the 12 volt power and maximizing the amount of amps that the 12 volt line carried. Since the introduction of multi rail power supplies, manufacturers have kept on adding more and more 12 rails, thereby consequently dropping the amount of amperage per 12 volt rail even lower. Consequently, upgrading your computer was made even harder because those power supplies just did not contain enough amps per rail to supply a particular computer component needed to be properly powered.

Well, today I am going to show you another multi railed PSU, this one built by Seventeam. This time Seventeam made this PSU having only 2×12 volt rails. Seventeam not only reduced the amount of 12 volt rails, they made this beauty a modular design. This should help out by taking a lot of the guess work out and helping out on the confusion when purchasing a new power supply.

About Seventeam

Seventeam Electronics is founded in 1986. Its headquarters and R&D center are based in Taipei and currently has instant sale and logistics network in major countries around the world.

As everyone knows, Seventeam Electronics is the leading company in switching power supply products. Its leading expertise also dominates the markets in developing high performance, high watts, high stability and environmental product. It promotes the technology that is quiet and energy smart, furthermore, it tried hard to promote the concept of Semi-Fanless innovation. These features of the company are undoubtedly the strong forces in driving computer user experiences and the industry itself forward in the age that emphasizes computer speed.

The power supply products we offer include the power supply for PC and customized power supply for IPC (for industrial and server uses). We dedicate ourselves in promoting the global sale and service network of all Seventeam’s products. Our products are used by various global leading partners in system integration and we also offer multi-faceted OEM.ODM services.


Model No ST-850Z-AF
Output Wattage 850W
PFC Active PFC
Efficiency > 80 % FULL LOADING
Noise Level dB at W LOAD
P. G. signal 100-500 ms
Hold-up Time 12ms at 25℃
Weight 3 KG
Color Black
Fan Single 135 mm DC Fan
Dimension 163mm (L) x 150mm(W) x 86mm(H)
Protection OCP、OVP、UVP、OPP、Short Circuit Protection
Input Voltage 90-264 VAC
Input Frequency 50 ~ 60 Hz
MTBF 100,000 hrs minimum (at 25 ℃)
Input Current 113-7A
Protection OCP、OVP、UVP、OPP、Short Circuit Protection
Input Voltage 90-264 VAC
Ouptut Voltage
Voltage +5V +12V1 +12V2 -12V +3.3V +5Vsb
MIN 1 1 1 0.0 0.5 0.0
NOM 15 15 17.5 0.4 12.5 1.5
MAX 30 30 35 0.8 25 3


Well we need to start somewhere, so let’s start off with the packaging.

Now, as we can see, the product box is slightly bloated from the looks of it. Kinda makes you wonder what’s in the box to make it bow like this. Well, looking at the top of the box we have the name of the PSU V-Force in the center of the box. To the left of this name we see an image of the PSU itself. Listed at the bottom of the box, is model type Z-AF/P-AF, and that this PSU is modular, SLI/Crossfire capable, PCI-E 6+2, and that the fan is either 120mm, or 135mm. Also, I forgot to mention to the very top, on the left we have the company behind this PSU, Seventeam, and that this is an 850 watt power supply.

Flipping the box on its side, we can see Seventeam listed the general features of this PSU.

Turning the box to 90° we see that Seventeam listed the Voltages and amperages here. This model of PSU is an 850 Z-AF (designated by the orange sticker.)

The energy saving capabilities of this PSU and the Fan chart.

The back side of the box has several languages listed, giving us the general features of this PSU.

Upon opening the box, we see that Seventeam just did the bare minimum, as far as packaging itself. Just using two pieces of foam rubber on the case of the PSU. We see a black bag up towards the upper part of the box. Then some wires that come out of the PSU, and, of course, the instruction booklet.

Better look of the internals of the box before removing everything.

Here are the contents of the box laid out. Now we notice that Seventeam wrapped the PSU in a plastic bag to help keep dust and other small particles for getting inside the PSU during shipping and a power cord for which we will need to hook the PSU to the house. But again, nothing really fancy here other than a velvety black bag on the far left side.

The black bag contains the other cables that you can hook up to the PSU if, and when, they’re needed. Until then, we can keep these in this bag. Nice thinking, Seventeam.

Looking through the back end of the PSU.

Looking through the blades of the fan into the PSU.

The voltage table and amperage rating of each voltage. Notice this PSU uses only 2×12 volt rails.

This is where we will hook up the extra cables that are in the black bag. Seventeam conveniently named each plug for us so we know what cable goes where.

This PSU is not fully modular, There are four sets of cables coming from the PSU itself. Those cables are the Main 24-pin power plug, the EPS 8-pin CU plug, and two 6+2 PCI-E power plugs. The modular plugs are 2 x 3 4-pin Molex plugs, 2 x 3 SATA plugs, and 2 extra 6+2 PCI-E power plugs. If you notice, these cables stretch out quite far. We should have no problems using this PSU in a large chassis.

This PSU has up to four 6+2 PCI-E power cables, two of which are hard wired into the PSU itself. The other two are of a modular design.

The 2 x 3 SATA cables (Modular)

The 2 x 3 4-pin Molex cables (Modular). Now one of these Molex cables has one floppy power plug.

The 24-pin Main power plug for the motherboard ( Non Modular).

The 8-pin EPS CPU power plug and 4-pin CPU power plug (Non Modular).

The hardwired power cables, which are one 24-pin main power cable, 2 x PCI-E 6+2 power cables, and finally the EPS CPU power cable.


I am going to install this PSU in my dad’s computer, being that my computer is just a tad too much for this PSU to handle.

PSU installed into the case.

Close up view of the PSU

All hooked up and ready to go. I could not get to the Mainboard’s EPS CPU power plug easily as I did not want to rip apart the entire internal of the case to route the EPS CPU power plug. So I just hooked it up this way.

To the left of the Noctua CPU cooler is the EPS CPU power plug. It’s a tight fit even in a Cooler Master ATCS 840 chassis.

Even though this PSU is not fully modular, it still makes my cable management abilities look good. I have bad cable management abilities.


Test Setup & Testing Methodology
CPU Core 2 Quad Q6600
Motherboard GigaByte P45 Extreme
Case Cooler Master ATCS 840
Memory Mushkin 1600
Video Card Sapphire 4870
Hard Drives 1 x 160 Gig Sata2 Western Digital, 1 x IDE Maxtor 60 gig
CDRom Drive Lite On Sata1 DVD Burner
Power Supply Silver Stone OP850, Seventeam 850
Type Of Coolers Used Noctua CPU cooler, SilenX GPU cooler
CPU Speeds Used 3.0 GHz
Operating System Used Microsoft Windows Vista 64 bit Ultimate
Type of Software Used During Testing Prime95, WinRar, 3DMark06

During my testing portion I would measure each individual power supply line, the Molex’s, SATA power cables, PCI-E power, EPS CPU power, 24-pin main power. I used WinRar for HDD testing, 3DMark06 for the video card, Prime 95 for CPU. Each time I ran a test I not only checked that power plug, I would check the 24-pin Main power. Since my EPS power plug on the motherboard was hard to get to, I ended up poking a small hole in the the + (yellow) wire sleeve of the cable itself. I used a Multimeter to perform all of my measurements of each power cable, nothing else was used. The lowest voltage was recorded after testing each power cable three times.


Seventeam 850 watts Silver Stone 850 watts
OutPut Power Idle Load OutPut Power Idle Load
24-pin Main 12 volt 12.4 12.37 24-pin Main 12 volt 12.14 12.15
24-pin Main 5 volt 5.17 5.17 24-pin Main 5 volt 5.06 5.06
24-pin Main 3 volt 3.41 3.4 24-pin Main 3 volt 3.38 3.36
EPS CPU 12 volt 12.39 12.35 EPS CPU 12 volt 12.16 12.13
PCI-E 6-pin 1 12 volt 12.38 12.35 PCI-E 6pin 1 12 volt 12.13 12.11
PCI-E 6-pin 2 12 volt 12.38 12.35 PCI-E 6-pin 2 12 volt (same cable) 12.13 12.11
PCI-E 6-pin 3 12 volt 12.37 12.36 PCI-E 8-pin 1 12 volt 12.16 12.13
PCI-E 6-pin 4 12 volt 12.37 12.36 PCI-E 8-pin 2 12 volt 12.15 12.13
Molex 12 volt 12.38 12.34 Molex 12 volt 12.15 12.14
Molex 5 volt 5.17 5.16 Molex 5 volt 5.05 5.05
SATA 12 volt 12.4 12.36 SATA 12 volt 12.15 12.13
SATA 5 volt 5.18 5.17 SATA 5 volt 5.07 5.06
SATA 3.3 volt 3.44 3.44 SATA 3.3 volt 3.4 3.4

As we can see, the Seventeam 850 watt PSU provides enough power to power just about anything in your computer, on both idle and load. On the 12 volt power lines, the most fluctuation I saw was a mere 0.04 volts. The 5 volt line barely budged 0.01 volts and the 3.3 line only moved by 0.01 volts. Now, we do notice the Seventeam 850 PSU does have a high voltage output. On the 12 volt line it’s over by 0.41 volts, 5 volt line by 0.18 volts, and the 3.3 volt line is 0.14 volts over. I myself, like to see these a little closer to the actual voltage, but this power supply is still well with in the safety limits of 5% +/-.


The Seventeam 850 watt PSU performance is on par with other comparable offerings. What separates this particular PSU from the other multi-rail PSU’s, is that this PSU only has two rails instead of the 4+ rails we have seen. By making two large 12 volt rails, this PSU will provide enough power to those components that need it, while at the same time taking the guess work out of what power cables are on what rail; Will this rail be enough to power my video card etc., etc. The feature I liked most about this PSU is that it contains four individual 6+2 PCI-E power cables, as this will make hooking up any type of video card easy and painless.

The only complaint I have is this PSU’s high voltage outputs on the 3.3 volts, 5volt, and the 12 volt lines. I prefer to have these a little closer to their actual voltage rating. Even I have to consider the simple fact that during my testing, this PSU barely fluctuated between idle and load, telling me that this PSU can provide my system with enough voltage, whether I am browsing the internet or getting in my slaughtering with my favorite game.

A quick look at Newegg puts this PSU around the $150 USD mark, which is more then fair enough to pay for a PSU of this quality.

We are trying out a new addition to our scoring system to provide additional feedback beyond a flat score. Please note that the final score isn’t an aggregate average of the new rating system.

  • Performance 9.0
  • Value 9
  • Quality 9
  • Warranty 9
  • Features 8
  • Innovation 8

Final score of 8.0 out of 10 and receives the Bjorn3D Seal of Approval.

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