Posted On: Sun, Jan-25-2009
Reviewer: OklahomaWolf
Product: Seasonic SS-400H1U
Product Link: http://www.seasonic.com.tw/product/ipc_1u.jsp
Supplied By: Seasonic
Price: $87.33 @ Provantage

Introduction

Seasonic came to me a little while back and offered me a chance to look at two of their more recent offerings. One of those was the 850W M12D I looked at a few weeks ago, and the other is today's review specimen: a server oriented 1U form factor unit that weighs in at 400 watts. Are Seasonic's server units as good as their consumer level products? Today's the day I at last answer that question.

Page 1 -

Seasonic power supplies come in all shapes and sizes. Why, once I saw one that even looked like a poodle, I did. But today, I'm not going to be looking at that one, with my apologies to any canines who might be reading this. Instead, I'm looking at one of their server models.

The unit in question is the SS-400H1U. As the nomenclature implies, this unit is 1U form factor to signify its compliance with 1U rack mount cases. The 1U refers to the height of the case - 1U is about 40mm high, with 2U, 3U, and so on being multiples of that number.

This unit isn't quite the highest power 1U power supply on the market, and not even the highest capacity from Seasonic, but it's no slouch either. It's hard to get a lot of juice into a case this big, and Seasonic did their best on this puppy. When you consider the fact that these things need to operate at high temperatures for months on end, they definitely had their work cut out for them.

Because this unit came with no fancy box full of marketing bullet points, I'm electing to reprint some of the info from the datasheet itself for you, where there are some things to brag about:

  • Forward converter circuit - means this could be very efficient
  • Super high efficiency and reliability for industrial level
  • Easy swap connector design - you can see the modular connectors in the picture above
  • High reliability ball bearing fan
  • Low ripple & noise - we'll see about that on page two
  • Smart & silent fan control (S2FC) - this is the same fan controller on most of Seasonic's consumer level offerings... not that most server units need to be silent
  • Zero minimum load on 3.3V rail
  • Short circuit protection on all outputs
  • Over voltage protection
  • Over power protection

Well, that's most of it. I was disappointed to find no mention of full power operating temperature, but since this is a server unit I'll do my best to heat it up in the hot box and see how it does. It is reasonable to expect full power for something like this to be achievable at fifty degrees Celsius, and I aim to see if it can do it.

Here's the exhaust end of this unit, along with a good look at the two 40mm Superred CHA3812DB-O fans. I have to say with these wee little noisemakers, it's not too likely Seasonic's fan controller is going to keep them very quiet.

And here's our label of the day. There's not too much interesting up there, as this is pretty much your standard ATX power supply in a different form factor. Combined 12V capacity is an adequate 348W, while the low 3.3V/5V combined rating makes this unit an unwise choice for old Pentium III's. Not that they're making new 5V based chips like that anymore.

But wait, there is something interesting up there after all - the 80 Plus logo. In fact, the unit is certified by them to pull in at least 80% at 20%, 50%, and 100% of full power. This is good news for a unit this size, as higher efficiency means less heat generated.

Seasonic SS-400H1U +3.3V +5V +12V1 +12V2 -12V +5VSB
20A 21A 16A 17A 0.8A 3A
Max Power 130W 348W 9.6W 15W
400W

And finally, here's the cabling. No sleeving for this puppy, but I do have a warning for you all. The power supply end of these cables uses Molex Mini-Fit Junior type connectors. The ATX cable goes into a 22 pin connector (bottom left), the 12V connectors go to a 20 pin connector (bottom right), and the peripheral connectors go to the 24 pin top connector.

As connectors go this is pretty idiot proof, but when dealing with that ATX cable, make sure you plug in the right connector. It's possible to plug the wrong end into the top connector, and you don't want to do that. So do make sure you're plugging only the 22 pin end of that cable into the appropriate connector on the PSU m'kay?

Type of connector: Seasonic SS-400H1U
ATX connector (300mm) 24 pin
8-pin EPS12V connector (450mm) 1
4-pin ATX12V connector (450mm) 1
5.25" Drive (350mm+150mm) 2
5.25" Drive (450mm+150mm) 3
3.5" Drive connectors (+150mm) 1
SATA (450mm+150mm) 2
2 x 3 PCIe (600mm) 1
Unit Dimensions(L x W x H)
235mm x 100mm x 40mm

As you can see, the cables aren't all that long but there is enough there to be functional in the cases these are designed for, and there are enough connectors to get the job done as well. I was pleased to see the inclusion of a PCI-E 6 pin connector, even though most servers likely won't need a video card powerful enough to require one.

You may notice that I haven't detailed which 12V rail powers which connector this time. The reason for that is, this unit does not actually have dual 12V rails. It's single 12V all the way back to the secondary side Schottkys, with no OCP employed to split them. That makes things easy for testing.



Page 2 -

Normally, this is where I go into a great big typing frenzy to detail just what the plan is to load test the unit at hand using my trusty SunMoon SM-268 ATE, Brand 4-1850 power meter, USB Instruments Stingray O-Scope, customized LM35 based temperature monitor, and a DMM. But to be honest - this time I'm feeling lazy, so I'll make you read all about it in last week's review here.

The difference from last week's review is that I can sum the 12V rails down to one without worry, because this is only a single 12V unit to begin with. Otherwise, everything stays the same for the progressive and crossload load testing keeping in mind the maximum load specs for each rail.

Results from Seasonic SS-400H1U COLD load tests
Test # +3.3V +5V +12V DC Watts/
AC Watts
Eff. Intake/
Exhaust
Simulated system load tests
Test
1
3A 3A 6A 117W/
144W
81.3% 19°C/
26°C
3.30V 5.00V 12.08V
Test
2
4A 4A 10A 173W/
205W
84.4% 19°C/
28°C
3.30V 4.99V 12.06V
Test
3
5A 5A 14A 230W/
270W
85.2% 20°C/
30°C
3.30V 4.98V 12.06V
Test
4
6A 6A 20A 312W/
368W
84.8% 20°C/
34°C
3.30V 4.98V 12.04V
Test
5
8A 9A 25A 396W/
476W
83.2% 20°C/
36°C
3.29V 4.96V 12.02V
Test
CL1
15A 16A 2A 172W/
222W
77.5% 20°C/
33°C
3.29V 4.95V 12.08V
Test
CL2
1A 1A 29A 376W/
446W
84.3% 20°C/
35°C
3.30V 5.00V 12.02V

We're off to a very impressive start here. I'll comment on the voltage readings first by making you take a look at the 3.3V rail. We have 0.01V deflection there, people. That's better than 0.4% regulation there. When's the last time you saw something hold the rails that well? Actually I don't even know if I've seen something only drop the 3.3V by 0.01V before. And look at the other two rails - we're inside 1% on both of them. This is exceptional performance considering the power supply in question is a 40mm tall pipsqueak.

Things only get better when looking at the efficiency numbers, for indeed we see the unit making good on the 80 Plus numbers. That is, with the exception of crossload test CL1, which is a load this unit's never going to see in normal operation.

My general impressions of the fans were... they're not quiet. 40mm fans rarely are. They were audible in test one, and very audible in test five and CL2.

Overshoot Transient Testing - Seasonic SS-400H1U
VSB On
VSB to Full 12V
Off to Full 12V

Overshoot transient testing, where I check for power on spikes, is also very pleasing for this unit. Not once do the turn on spikes even get close to the spec, never mind exceed it, and there are no negative voltages present. Additionally, the spike itself is as smooth as I've ever seen it with no jagged edges at all. Just a gentle curve. It's like the PSU is listening to the Lite FM or something when you turn it on.

Indeed, while I was doing these tests I happened to drop my pen on the floor. I then let out a four letter word. The power supply actually told me to "mellow out, dude."

But I didn't mellow out, oh no. I locked the power supply in the hot box, is what I did. And here's what transpired:

Results from Seasonic SS-400H1U HOT load tests
Test # +3.3V +5V +12V DC Watts/
AC Watts
Eff. Intake/
Exhaust
Simulated system load tests
Test
1
3A 3A 6A 117W/
141W
83.0% 27°C/
28°C
3.30V 5.00V 12.08V
Test
2
4A 4A 10A 173W/
205W
84.4% 31°C/
36°C
3.29V 4.99V 12.06V
Test
3
5A 5A 14A 229W/
271W
84.5% 34°C/
39°C
3.29V 4.98V 12.04V
Test
4
6A 6A 20A 312W/
370W
84.3% 37°C/
43°C
3.29V 4.98V 12.00V
Test
5
8A 9A 25A 395W/
479W
82.5% 40°C/
53°C
3.28V 4.96V 11.98V
Test
CL1
15A 16A 2A 172W/
221W
77.8% 34°C/
40°C
3.27V 4.94V 12.08V
Test
CL2
1A 1A 29A 375W/
448W
83.7% 39°C/
45°C
3.30V 4.99V 11.96V

This time, I was able to make the 3.3V rail move a bit. But look, it's still within 1%. So is the 12V. In fact, only the 5V rail goes out of the 1% area, and even it doesn't get far. This is so far the most stable unit I've seen in a little while. While I never got it hot enough to see how it did at fifty degrees, I'm very confident you can expect it to perform very well indeed at those temperatures.

And look, the efficiency's actually gotten better in test one, though it's gotten a bit worse by test five (which can be expected due to the heat coming into the unit). You know what this means? Right - it actually passed 80 Plus Bronze guidelines for me once I got it heated up. That's excellent.

Oscilloscope Results - Seasonic SS-400H1U
Test #
+3.3V
+5V
+12V
Test
1
Test
2
Test
3
Test
4
Test
5
Test
CL1
Test
CL2

It was about this point that I got a Howard Jones song stuck in my head, for things are only getting better for this unit. Ripple? What ripple? The 3.3V and 5V rails don't have much of that. I'm talking well under 10mV here, people. 12V has a bit more than that by test CL2, but at 40mV it's staying at precisely at one third of the ATX spec. But I won't stop and falter, for this is more outstanding than Shaquille O'Neal rapping about being outstanding.

Say, that guy only has six inches or so on me... does that make me outstanding too? Or just under-standing? See... 'cause I'm... shorter than he is and... "shorter" could mean "under"... I'll shut up now. You can stop groaning.



Page 3 -

It's now time to not crack up, bend our brains, see both sides, and throw off our mental chains as we look at the guts of the Seasonic. Man... what is it with me and Howard Jones today?

As you can see, they crammed a heck of a lot of power supply into this little case. That heatsink with the holes in it is designed to contact the top cover, thus using it as an extended heatsink.

The soldering turned out to be the best I've seen on a Seasonic unit... better even than the M12D and much better than the Antec Neopower Blue. In fact, the soldering was so good I had trouble getting parts out of here, so I didn't get the part numbers of the PWM and PFC controllers this time.

There isn't much of a transient filter this time, because this unit relies on the combo line filter and AC receptacle to provide some of that functionality. Still, there is a MOV, a coil, two X capacitors, and two Y capacitors here.

That's a Nippon Chemi-Con main filter capacitor there.

The heatsinks are out and it still looks packed in there, doesn't it? In this shot, the secondary side's on the left of the central transformer, while the primary is on the right.

Secondary capacitors are mostly Nippon Chemi-Con with a Rubycon or two thrown in for good measure.In the bottom center of this picture you can see the three chokes (the ones with blue cores) that signify independent voltage regulation.

Here are the two heatsinks and their attached parts, which took entirely too long to desolder. Up top is the secondary heatsink. It carries two 30A50CT's for the 12V rail, and one STPS30L30CT each for the 3.3V and 5V rails.

The bottom heatsink has all the primary side parts. There are to FDP18N50's and a diode for the PFC, and two more FDP18N50's in double forward for the main switchers.


Time for some scoring. Since this is a server unit, I'm going to do this the same way I did the IStar Claypower review. No aesthetics score.

Performance (40% of the final score) - the Seasonic SS-400H1U managed to do something I was hoping to see already from the aforementioned Claypower: it handed in impressive performance on all fronts. Considering the environments these are designed for as well as the fact that the attached hardware needs to be up and running as long as possible, my expectations are high when it comes to units like this. I've handed out the occasional perfect score here before, but none yet to a unit like this. So, this unit becomes the first of its kind to get a 10 from me.

Functionality (30% of the final score) - here again the Seasonic one ups the IStar. Not only does it have enough cabling to get the job done, it's modular too. And it has a 6 pin PCI-E connector for good measure. That means another 10.

Value (30% of the final score) - you can get these right now for $87.33 at Provantage. That's very, very good. Considering big brother 520W is floating around just north of the $100 mark, I don't see any compelling reason you shouldn't just up and get a pile of Seasonic units if you're in the need for powering a bunch of 1U servers. 9.

Performance

10

Functionality

10

Value

9

Total Score

9.7

Summary

In my second ever review of a dedicated server unit, Seasonic has managed to not only impress me but they've also set the bar for anything else aiming to compete in this market. In every way I can think of, it simply excelled. I'd love to see something better than this come through here, but I'm not going to hold my breath waiting.

The Good:

  • almost nonexistent ripple and noise at 3.3V and 5V, and not much at 12V
  • highly efficient
  • quieter than the IStar was

The Bad:

  • 40mm fans are incapable of being silent

The Mediocre:

  • Howard Jones won't leave my head. I suppose no-one is to blame.




This review was provided by : JonnyGURU

The URL for this review is :
http://www.jonnyGURU.com/modules.php?name=NDReviews&op=Story&reid=131