Reviews - SevenTeam ST-500EAZ External Power Supply
Sample Provided by: SevenTeam (By Tazz on Mon, Mar-27-2006)

Page 1 -


The front of the unit during the first few minutes of test one. The room was 25 °C, but that quickly changed.

It's not very often I get to review a truly "novel" power supply unit. But this weekend I'm taking a look at an external power supply unit from the folks over at SevenTeam Electronics.

The way this unit works, there's a metal plate with cables for PC peripherals that bolts in place of a typical power supply. This unit then sits outside of the PC and connects to the back of that plate with a set of three modular cables.


This is the back of the ST-500EAZ.

The concept behind this is to move the heat generating power supply to the outside of your heat generating PC. By self-containing the power supply, the only heat the unit is subject to is it's own.


The bottom of the unit features gold trim rubber feet reminiscent of better audio equipment.

I'm sure a lot of you are aware that I have a bit of an affinity with SevenTeam. In my experience, SevenTeam makes very solid, highly efficient units. Unfortunately, their representation in the United States gives Seventeam a bit of a bad rap. It seems that almost all of their products are "over-rated." The Cooler Master eXtreme Power 600W is actually only a SevenTeam ST-500BKV, the XG Duro 900W is actually only a SevenTeam ST-750EAJ. Where long hold up, continuous rated power is what's typically put on the label by SevenTeam, it seems that a 500ms peak power is what's put on the label by the importers.

About the only "honestly" rated SevenTeam re-label I've seen has been the Sytrin Nextherm 460W, but because of it's "honest labeling" sales may be suffering. In fact, I have a friend at a reseller that told me that he had to drop the unit from his power supply line up, because it was considered over-priced for a 460W unit. It's ironic that if Sytrin just slapped a 550W sticker on the side that they would be doing nothing different than what the folks at Cooler Master and MGE/XG are doing and the product would likely sell like hot cakes.

The way this external unit is marketed in the U.S. doesn't seem to be any different than the other SevenTeam built products I mentioned. This unit is sold by the XG division of MGE as an external 600W unit. If we have a look at the label on the unit Gabriel Torres' previewed at Hardware Secrets, we can see the same "ZJB500EAZ" serial number prefix underneath the rail table that we seen on the SevenTeam label above.

Specifications as per the PSU label:

Seventeam ST-500EAZ +3.3V +5V +12V1 +12V2 -12V +5VSB
28A 30A 18A 20A* 0.8A 2.5A
Max Combined Watts 150W 456W 9.6W 12.5W
478W 22W
500W
* Shortly after I received my sample, the specs on the SevenTeam website showed this unit with 22A on he +12V2.

Seventeam calls this PSU "semi-fanless." There's a big honkin' 80MM fan inside the housing. The fan doesn't spin often. In fact, in normal PC use the fan only spins during heavy battle. Web surfing, word processing and the like should not provoke the fan to turn on. Furthermore, when the fan is spinning, one can barely hear it, probably because it is not mounted to an outside panel of the unit. It's stashed just behind the front LCD panel, directly in front of the heat sinks.


Yes Virginia. There IS a fan inside. We'll look at more inside shots later...

Speaking of LCD; just in case the fact that there's a big aluminum box sitting on top of your case wasn't cool enough, the LCD on the front of this unit tells the user the ambient temperature of the power supply, the estimated power output of the unit and at what voltage one of the 12V rails may be at. We'll discuss the LCD a little more later.

For now, let's have a look at those cables... starting with the three thick external cables...


The wire colors tell us that this isn't your typical pinout.

The external cables use standard connectors, but they are quite proprietary. The pinout on the back of this unit is unlike any standard in the industry. Why are there three external cables? I'm not sure why they didn't just do two (like two 24-pin cables) or even one big one (like put two 24-pin cables in one casing) but there are three thick cables with nearly unfinished ends (they could've done better than heat-shrink, in my opinion.)

Another thing to note is that these cables are only a little over a foot long, so the unit isn't going to go far from the rest of your PC. It's likely to just sit on the top of the case. I don't believe you're going to be able to put this box on the floor next to your PC unless you have an upside-down case and it's not going to make it to the top of your desk if you keep the rest of your computer down on the floor.


The cables aren't very long and therefore do not allow for very remote location of the power supply.

The cables on the inside of the PC are a whole other story... one with a very similar plot....

The cables that enter the inside of the case are simple sleeved units. Again, with ends that are hardly beauty pageant material. Like the external cables, the ends are heat-shrink wrapped with a considerable amount of wire exposed. Regardless of how the internal cables are decorated, I had to think about why they wouldn't go with a modular interface inside.

Certainly with a modular interface on both the back of the power supply and the back of the case, there would be considerable resistance created by adding yet another modular interface. But with fixed cables inside and no power supply in place to tuck cables up on top of, the user is left with a real mess inside their case. What they should have done is made at least one end of the OUTSIDE CABLES fixed. You need all three. You're not going to "use only the cables you need" on the outside, and if the cables on the outside were fixed, they'd look better too! This is a major fubar on SevenTeam's part and it's going to make judging aesthetics difficult. Certainly, the cool factor of having a power supply on top of your case with a glowing blue LCD is high on the bling-o-meter, but all of this cable mess makes me want to vomit.


The above metal plate bolts in place of where a power supply would normally go.

Cables included with power supply:

Type of connector: Seventeam
ST-500EAZ
ATX connector 20+4 pin
2 x 2 12V connectors 1
2 x 3 PCI-e 2
8-pin Xeon/EPS connector 1
6-pin Xeon/AUX connector 1
5.25" Drive connectors 6
3.5" Drive connectors 2
SATA Drive power connectors 2
Fan only connectors (thermostatically controlled 12V only) 0


The +12V 4-pin and EPS 8-pin are paired up on the same cable.


The two PCI-e's are also on the same cable. I'm not sure I like that idea.

We're almost to the load tester portion of the review.....

I decided it might be neat to graph the actual wattage vs. the wattage displayed on the LCD. So on the next page you'll see that there's two columns. One labeled "actual wattage" and another labeled "watts displayed."

The numbers you see on devices like Thermaltake's"Total Watts Viewer" and Cooler Master's "Total Power Consumption Display" are rarely accurate. The display on the ST-500EAZ isn't really any more accurate. But there's good reason for this.

Have any of you guys ever installed an ammeter in a car? Remember how the ammeter hooked up between the battery's positive terminal and everything else in the car (typically an older car or your weekend race car w/ minimal electronics)? That's how it measured amperage. Because all of the amperage of the car's electrical system goes THROUGH the ammeter, it can tell you how much juice your car is pulling from the battery. But if you hook something up that by-passes the ammeter, you can't gage it's usage.

For a power supply to accurately tell you how much wattage it's using, it would have to measure all of the DC amperage being pulled from each peripheral connector. And because a power supply supplies multiple DC voltages, you'll essentially need an ammeter for each rail. Multiply the Amps you've measured by the voltage of each rail, add them all up and there's your total wattage. Guess what? It's quite possible, and there are devices that will do this, but it doesn't fit in a standard ATX power supply housing... or a Seventeam external power supply housing for that matter.

What is typically done when a power supply has a wattage display is the AC input wattage is measured with a built in ammeter. A calculation is done to take the particular unit's efficiency into account. It is the sum of this equation that is displayed. So not only is the number going to be off because efficiency can vary based on temperature, but because efficiency is not a linear number. It is actually on more of a bell curve as load varies (typically low efficiency on low and high loads with the better efficiency in the upper 70% of the power supply's capability,) the number on the display can be quite off.


The power supply, simply plugged in, shows a 22W load from the +5VSB.

So now for the load tester portion of the review....

If you're not familiar with the way I load test power supplies, I'll explain. I'm in possession of a SunMoon SM-268 power supply load tester. It's the kind of equipment power supply manufacturers use to quality assure units. My tester allows me to pre-program five different loads on six different rails at a time. The load tester can then report the voltage of each rail it's loading.

I typically keep -12V with a .5A load and +5VSB at 2.5A. The other four rails are the ones I fluctuate for testing purposes. Those rails are +3.3V, +5V and the two +12V rails. Each test is run for an hour before readings are logged.

I run the power supplies on a bench in a 25°C room. Normally, that's a flaw in my testing methodology because the power supply I'm testing isn't sucking up the heat coming off of whatever I'm powering (I really should make a duct going from the load tester's exhaust fan to the intake fan of the power supply.) But since I'm looking at an external power supply and the hottest thing in the room IS the power supply, the fact that the power supply sits on a bench doesn't really matter!


 

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