Rosewill Silent Night 500 W Fanless Power Supply

Sometimes even a quiet fan is too loud and for those situations Rosewill has you covered with their Silent Night PSU. It doesn’t have a loud fan. It doesn’t have a quiet fan. It doesn’t have a fan at all! The claim is that this makes it a 0dB PSU. It certainly goes a long way towards that goal, but fans aren’t the only source of noise from a PSU.

Features and Specifications

Rosewill.com’s product page is amazingly brief. There isn’t a features list, just a brief, incomplete, specs table. As such I’ve gone to Newegg’s product page and found a more complete list.

• 500W Power Output with Single Strong 12V Rail The Rosewill SilentNight-500 power supply delivers rated 500W of safe, reliable output for your computer systems. One single strong +12V rail with 4x 6+2-Pin PCIe connectors can juice up your high-end CPU and even multiple graphics cards.
•  Fanless Design Instead of traditional active fan cooling, the Rosewill SilentNight-500 adopts an 0dBA fanless design letting you operate your PC in a complete zero-noise environment. A great number of venting holes on walls and large heatsink on cover ensure effective and efficient heat dissipation.
•  80 PLUS Platinum Certified The 80 PLUS Platinum certified power supply provides ultra-high power efficiency of 91% at 20% load, 92% at 50% load, 90% at 100% load, saving your money on your electrical bill, reducing heat in your computer’s system and prolonging its life.
•  Modular Design With fixed 1x 20+4-pin main connector, 1x 12V 4+4-pin connector and 2x 6+2-pin PCI-e connectors, the modular design allows use of only the cable you need for
•  Superior Components All Capacitor are made in Japan with higher stability and longer lasting.
•  Comprehensive Protection An array of protection measures such as OVP, OPP and SCP provide maximum safety to your critical system components.

Single rails are not better than properly done multiple rails. Fanless is pretty awesome, if it works. We’ll see. For 0dBA (silence!) it’ll need to be free of whines and clicks and such too. 80+ Platinum is great. Modular is great, too. Japanese capacitors? Great! Comprehensive Protection? Also great. I’ll probably check SCP on this one too, just for giggles. Below are the specs, my thoughts are in italic text.

I don’t know whether to blame Rosewill or Newegg for the dubious English skills. Someone has them, though. Ideally that just means that the time and effort went into the PSU rather than marketing. I’d be OK with that.

Photos Part One: The Box

Much like the Tachyon 1000 W unit I reviewed, the box is a simple affair. I like it. Also similar is the foam packaging inside the box, I like that too. Rosewill is doing it right with the packaging here in my opinion, inside and out. Pretty short section, this.

Photos Part Two: The PSU

Here’s where things take a turn for the snazzy. Instead of a fan on top we have a massive heatsink! Also lots of ventilation holes. Do be aware that when I say “top” I mean it, putting this PSU in upside down could be a rather serious error. I don’t think I’d use it in cases with a top mount PSU either, unless you have strongly positive or negative airflow set up, or the entire top of the case is mesh and you mount the PSU heatink-up. While it doesn’t need a fan, it does require airflow. It should be able to generate enough convectively if there is room for the air to go somewhere, hence the top of a case not being a real great place. I’ll be rather rude to it in TEUW during testing, we’ll see how it does.

The output end of things gets it’s own selection of pictures.

Someone in the factory put one silicone modular plug cap on upside down, which I find amusing. It’s so far from being an issue as to almost be unmentionable. I mention it because, as I said, I find it amusing. The plugs look the same as the Tachyon’s plugs, a quick comparison between the two shows them to even be wired the same way. Despite this I don’t recommend mixing and matching cables between PSUs. In this case it would probably work, in other cases it can destroy the PSU and anything plugged into it. This happened recently on the forums.

A few angled shots:

Pretty nice looking. I’m a fan of crackle-black as well as of large heatsinks.

Photos Part Three: Cables

We’ll start with the hardwired jobs.

The sleeving starts well back from the end of the cable on the cables with split connectors, this makes it easier to get everything lined up right. It also makes it not look as good. The PCIe cables are somewhat dubiously done, functional enough, but kind of ugly. Onward to the modular cables and accessories!

For modular cables we get another PCIe cable with two 6+2P plugs, also with somewhat dubious +2P bits. Again totally functional, but not pretty. We also get a Molex cable with three Molex plugs and a FDD plug, a SATA cable with four SATA plugs, and a combo cable with two SATA plugs and two Molex plugs. I like the selection. We also get some cable ties, a power cord (don’t laugh, not all units come with one), four thumbscrews and four normal screws. I like that you get thumbscrews and normal screws, it’s a nice touch.

Testing Part One: Regulation Testing

A decent load test of a PSU requires a decent load. Contrary to what some may believe, that means you need a known load that can fully stress the PSU. Computer hardware does not cut it. Worse, if the PSU fails during testing it might take out the computer hardware anyway. Commercial load testers cost a lot of money. I do not have a lot of money, so I built my own with juicy power resistors and a Toyota cylinder head. It works great. I’ll be using it to load this thing down fairly severely and will check voltages and ripple (more on that later) at various points. The down side to my tester is that the loads it can put on PSUs are fairly coarse, they go in increments of 48 W for 12 V, 50 W for 5 V and 22 W for 3.3V. Those wattages assume the PSU is putting out exactly the official rail voltage, a PSU putting out 12.24 V rather than 12 V will be at 49.9 W per step rather than 48 W. I file that under the “tough beans” category as I figure if a percent or two of load makes that much of a difference, the PSU manufacturer should have hit the voltage regulation more squarely. It does make calculating efficiency difficult at best.  However, given that the input power is read via a Kill-a-Watt, the efficiency numbers are dubious to begin with. Kill-a-Watts are not known for extreme accuracy on things with automatic power factor correction. For this reason, I am not listing the efficiency.

The ATX spec says that voltage regulation must be within 5% of the rail’s official designation, regardless of load. It doesn’t actually mention that the PSU shouldn’t explode, though I expect they figured it was implied. Exploding is a failure in my book regardless.

It is also worth knowing that I will be testing this PSU at both outdoor ambient temperatures (typically between 10 °C and 20 °C here this time of year) as well as in the Enclosure of Unreasonable Warmth. TEUW is a precision engineered enclosure that I use to route the exhaust air from the PSU right back into the intake fan, it is adjustable to hold the intake air temperature at (almost) any level I want it. This way I can test the PSU’s response to hot conditions as well as cold conditions. For the hot testing I will be running the intake temp as close to the unit’s maximum rated temperature as possible. TEUW, in case you’re curious, is a cardboard box.

Unlike usual, the first temperature number is the heatsink on the top of the unit. The second temperature is just outside the exhaust grill. Due to the fan-less, efficient, nature of this unit I wasn’t able to get it as hot as I’d have liked to, nor was I able to get it as hot or track the temperatures as well as I’d have liked due to the large delta between air temps at the top of TEUW and at the bottom where the probe was.

It really is silent. No whines, no squeals, no fan, nothing. Impressive. 12 V regulation was 0.4%, excellent. 5 V regulation was 1.3%, which is good. 3.3 V regulation was 1.5% which is also good. All told that’s 1.09% regulation, just shy of the 1% “AWESOME!” number, but very good indeed. The heatsink on the roof stayed a fairly consistent 10-12 degrees hotter than the air going in the exhaust grill, once I isolated it from the world’s breezes. I don’t think this unit would have any issues in a fan-less case, as long as the case is open enough for convective air movement.

Last, this unit does have functional SCP, though it appears to take the form of tripping the OPP sensing bits as it takes a bit (I’d guess 50-100 ms) to kick in. It works though, which is nice.

Testing Part Two: Ripple Testing

Ripple is fluctuation of the PSU’s output voltage caused by a variety of factors. It is pretty much impossible to have zero ripple in a SMPS computer power supply because of how a SMPS works, so the question is how much ripple is there? In the regulation testing phase we found out how the PSU does at keeping the average voltage at a set level, now we’re going to see what that voltage is doing on really short time frames. The ATX spec says that the 12 V rail cannot have more than 120 mV peak to peak ripple, the 5 V and 3.3 V rails need to stay under 50 mV.

If that isn’t complicated enough for you, there are three forms of ripple to keep track of as well. Long-term ripple from the PSU’s controller adjusting the output voltage and over/undershooting, correcting, overshooting, etc. Medium-term ripple from the voltage controller charging and discharging the inductor(s) and capacitor(s) that make up the VRM, and very short-term ripple caused by the switching itself. The first and second forms are the most important, if they are out of spec it can cause instability at best or damage in extreme situations. The very short-term (I call it transient ripple) flavor is less crucial, excessive amounts can still cause issues though it takes more of it to do so. The ATX spec does not differentiate, as far as the spec goes 121 mV of transient ripple is just as much of a failure as 121 mV of medium or long term ripple.

I test ripple in a few difference ways, first I test it during the cold load testing. It is tested at zero load and maximum load first. During the hot load testing I test the ripple at maximum load again. I have recently started testing ripple at fairly random loads with the unit still hot, it’s a bit unorthodox (a bit? maybe a lot) but has found issues in the past that did not show up with other test methods.

First up, cold zero load ripple. Scope is at 5 ms / 10 mV, except for 3.3 V which is at 5 µs / 10 mV to show the transient spikes. 5V has ’em too.

Nice looking, especially 12 V. The spike in 3.3 V and 5 V isn’t an issue as it’s still well within spec. Where it’s coming from I don’t know. APFC switches come to mind.

Next up, full unit load cold. Scope at 5ms / 10mV for 12 V and 5µs / 10mV for 5 V and 3.3 V.

At full load the ripple levels are still well within spec. Right about 33% of maximum for 12 V, while 5 V and 3.3 V are a bit over 50% maximum due to the transients. The transients are about 400 ns long, it looks like a MOSFET or diode switching spike. In any case, these are good results.

Next up, a hefty 12 V crossload, still cold ambients, scope is at 5µs/10mV for all shots.

The same spike shows up here, without it the 5 V and 3.3 V ripple would be glorious. With it, it’s still better than average. 12 V looks great.

Next up full unit load at high temperatures, scope is still at 5µs/10mV for all shots.

New shapes, pretty much the same ripple levels. It likes it hot for the most part, that’s good as it’ll be at least warm without airflow. I’m pretty impressed really. The hot crossload results were unremarkable enough that I’m not going to waste everybody’s time with them.

Dissection

Disclaimer: Power supplies can have dangerous voltages inside them even after being unplugged, DO NOT OPEN POWER SUPPLIES. It’s just not a good idea. Opening a power supply and poking around inside could very well kill you. Don’t try this at home. Don’t try this at work. Just don’t do it.

This PSU has quite a few more screws than normal, the sides are their own plate of sheet metal, plus of course there’s the big heatsink on top. Amusingly I suspect you could get it apart without killing the warranty sticker, though I don’t recommend it.

The bottom of the heatsink is a simple plate, connected to the primary and secondary heatsinks with a thick thermal pad, the main transformer has an aluminum block on top of it with a pad to the heatsink as well. Under the PCB are more thermal pads connecting the PCB to the case.

Lots of thermal pads around here!  Why that cap isn’t upright I don’t know, it could be. It’s not hurting anything being tipped over though. The wet looking marks are silicone oil squeezed out of the thermal pads. Not an issue. Slimy, though.

The transient filter is all on the PCB for a change:

Nice complete one too from the filter end of things, two inductors, four Y caps, 3 X caps and a fuse. No MOV or TVS Diode, be sure to use a surge protector!

The rectifier is a US30K80R (30 A, 800 V), APFC switching is controlled by a 1653A inside an EMI shield and lots of yellow plastic tape. The single switch is a 5R140P (23A@25ºc, 15A@100ºc, 550 V), while the diode is a CREE C3D10060 (10 A, 600 V). Nothing out of the ordinary here, though these are top line parts. The inductor is an interesting design. The capacitor got a heatshrink wrap for some reason, it’s a Nippon Chemi-Con 400 V 470 µF unit. Also note the thermistor and relay for inrush protection. Nice to see.
The primary switches are a pair of 5R199P (17A@25ºc, 11A@100ºc, 550 V) MOSFETs.

On the secondary side we have four 023N04N (90 A, 40 V) MOSFETs for rectification. There are also a couple plates that take heat from the heatsink and drag it into the PCB, where the pads on the bottom of the PCB can take it to the case to be disposed of.

PWM duties as well as protections happen inside a custom SuperFlower SF29601 IC, nobody knows anything about what actually exists inside it. The 5 V and 3.3 V rails are generated on a PCB just past the secondary heatsink, it has another heatsink bolted to it from the secondary heatsink side. As such, I can’t get any information off it at all. The output wires of the PSU are protected from the Evil Noisy MOSFETs by an EMI shield inside yellow plastic wrap.

All capacitors throughout the unit (electrolytic and polymer) are Nippon Chemi-Con. Top notch!

The modular output board is a tiny little thing, it has a few more filter caps on it.

The soldering on both PCBs is excellent, though there are a few leads that are longer than I’d like. The person in charge of trimming leads (what a job) must have been behind or something. In any case, no issues here.

Nowhere can I find a temperature sensor, leading me to the conclusion that there is no over-temp protection on this unit. That seems like a dubious idea to me.

Final Thoughts and Conclusion

I’ve been wanting to get my hands on a fan-less unit since I first saw them. Now that I’ve finally acquired one, I have to say I’m impressed with it. SuperFlower and Rosewill have done an excellent job here.

The cables have all the connectors a 500 W unit should have, including four PCIe 6+2 plugs rather than the more standard two. The PCIe +2P bits aren’t as smoothly done as they could be though.

The unit really is silent. I heard absolutely nothing out of it while running. At startup the relay that shorts the inrush protection thermistor clicks once, but that’s it.

As usual with SuperFlower units there isn’t a MOV or TVS Diode for surge protection. I don’t agree with this. Similarly lacking is a UL number anywhere on the unit. The lack of UL listing isn’t a problem though.

Regulation and ripple control are very good. No problems there.

It runs very cool given any airflow at all, and takes a very long time to heat up even inside a sealed box. I see no issue running this in a fan-less or low fan case, as long as there is room for convective airflow. The lack of OTP makes it important to be sure you aren’t setting the PSU up inside a sealed box.

Price wise, this is tied for the most expensive fan-less unit, with another SuperFlower built unit. This is the only unit with four 6+2P PCIe cables however. The other unit at $160 has two 6P and two 6+2P, while the less expensive units only have two 6+2P in total. I’ll call it a “good” value.

To summarize, there are pros:

• Fan-less. It really is silent.
• Lots of PCIe 6+2P connectors, good cable selection in general too.
• Very efficient.
• Looks pretty awesome.
• Very good ripple control and regulation.
• Soldering is good though.

There are a few cons:

• A few leads are longer than I’d like.
• PCIe +2P cable bits aren’t very pretty.
• No OTP means a bit of care in placement is a good idea.

All told this is an easy Approved stamp to give out. If you need a totally silent PSU, this is a unit very worthy of consideration.

–Ed Smith / Bobnova