SilenX 400 Watt Power Supply Unit Review

Admin - 2007-02-23 20:09:11 in Power Supplies
Category: Power Supplies
Reviewed by: Admin   
Reviewed on: November 25, 2003


Today we have with us another exciting review product. Sure, its not flashy, it doesn't glow and it certainly does not make a lot of noise, but this SilenX 400W PSU has a lot to offer. When most of us Overclockers think 'power' we think 3 things - Higher, Faster, Louder. Well, this PSU is about to change the face of what we're looking for. Rated at 14 dBa or LESS, this PSU is the quietest one on the market, bar none. At 14 decibels, its not a matter of how much you need to ramp it down to hear it - its a matter of checking to see if its still on! But can something so quiet be efficient and useful? That's what we're looking to find out!

Company Profile
Well, lets kick it off with the company mission statement (in picture form!) and the description of this product.

SilenX power supplies are simply the quietest active cooled power supplies on the planet! With a true <14 dBA noise level from 1m, it will blow away any other so-called "silent" power supply on the market today. Zalman? Nexus? Seasonic? There's no comparison. Under load, the difference gets even wider! Thanks to some innovative technologies, SilenX power supplies can not only run quieter than other power supplies out there, but do so with higher efficiency, greater reliability and better stability. All SilenX power supplies feature heat-hardened components designed to run in intense thermal environments and come standard with one of the most efficient fans on the market today. The unique fan blade design along with its high-tech hybrid immersion bearings and silicone composite fan vibration dampening system makes this the only power supply on the market truly aimed for the silencing professional. Used by major recording studios, acoustic laboratories and corporate computing ! environments, these power supplies are not for those looking for a cheap power supply...this is the real deal.


Input: 115/230V @ 50/60 Hz
Output: 400W
3.3V - 30.0A
5.0V - 40.0A
12.0V - 18.0A
<5% Load Regulation
<1% Line Regulation
Efficiency: 75% under load
Over Voltage Protection: 3.3V/4V 5V/6V 12V/14V
Over Power Protection: 105%~150% of max load

All SilenX power supplies come with 1 year warranty and include a power cord for the US/Canada market.


In-Depth Look

Well, this came to me wrapped in plastic in a basic brown box, and after sorting through the foam, we have...

Looks very nice - comes equipped with 6 4pin Molex connectors, 2 FDD connectors, a 20pin ATX, a 6pin AUX (when will they get rid of these?), and a 4pin 12V connector. The Molex/FDD connectors are set up as: 2 lines w/ 2 Molex 2 lines w/ 1 Molex, 1 FDD Kind of a strange setup if you ask me, but it worked out with my system setup, which was nice. None of the wires are sleeved, unfortunately. Pre-sleeved 20pin ATX cables are always a bonus, because sleeving them is often a difficult chore.

Now that we've seen the inside, lets take a look at what makes this thing tick. This would be an excellent place for a warning. If you don't know what you're doing (and most of the time, even if you do) DON'T DO THIS! Taking the cover off voids the warranty, but more importantly, even when it isn't plugged in, there's enough juice inside these things to seriously injure, if not kill you. So, take a look at my pictures and keep yer fingers out! Alright, so, looking at the guts of this thing, you can see its a very streamlined setup. Its packed in there, but its an excellent job keeping space open for airflow.

And stuck into the PSUs heatspreaders, you can see the thermistor for the SilenX fan. This is a good place to leave it, when the PSU is on, you can tell where it is placed is one of the warmer places on the PSU, allowing the fan to cool at proper speeds.

And, speaking of the fan, here it is. Its an 80mm SilenX Thermistor fan. Dual Ball bearing, and stuck into the PSU with rubber plugs to further minimize noise from vibration. Now, the problem with this is that rubber plugs are a bit thicker then normal screws, making for a tight fit in some cases. In mine, however, it was no problem.


Test Rig:
Okay, so it's nothing spectacular. I'm a student, so sue me.

Now, since we're looking for a real stable PSU to do overclocking with, I'll give you one guess what my first step was. Overclocking the FSB to 400, making for a 2.2GHz processor. Now we're ready to fly.

So, testing consisted of a lot of various stress tests. Motherboard Monitor 5 kept my highs and lows, and this is what I did. Watched The Matrix, burnt a CD of Classical Music, listened to a couple CDs, played Counter-Strike, ran the Burn In Test with SiSoft Sandra stressing all the various components I have, ran 3DMark 2001SE a couple times, and ran a search for all the *.dlls and *.exes on my computer, as well as running [email protected] in the background all the while. That should do it! Keep in mind a number of these were done at the same time, and some obviously we're done at separate times. So, lets take a look at the Highs and Lows for the Voltages coming out of this PSU.

On the 3.3V rail we see a low of 3.18V and a high of 3.25V.
On the 5V rail, we have a low of 5.16V and a high of 5.19V.
On the 12V rail, we see a low of 11.67V and a high of 11.86V.

Well, this is a bit strange. The 5V rail is reporting better the normal voltages, which is a good thing, because it leaves a nice amount of room for leeway. However, on the 3.3V and 12V rail, we see less then average voltages, which are sometimes signs of a weak power supply. However, in the entire time I was testing, I had no problems with abnormal shutdowns, and there was always adequate power no matter how much I had running at once.

I should note here, that after looking at a number of other reviews, this result is very inconsistent. I'm beginning to think that the NF7-S might have a bit of trouble reporting proper voltages.

Regardless, these are the results I got. Looking at them, they are all perfectly within the 5% margin of error as provided by the PSU, which makes for good performance. Whenever I tossed something at it, it tossed it right back.


After throwing everything I had at it, and then some, the SilenX 400W PSU laughed at me. I'm pretty impressed by this little grey box. The fan is beyond silent, the PSU itself is rock solid and I'd have to say I'd recommend it to anyone looking for a solid PSU. I will remark the 12V and 3.3V rails seems below average, but I never experienced any trouble with power requirements - its very stable. Sure, no flashy stuff hanging off of it, but a bit of sleeving and (if you're adventurous enough) modification, and that solves that.

The SilenX 400W Ultra Quiet PSU definately comes recommended by me. Its a solid piece of work, and is now the quietest (active) component in my computer!

After a bunch of research, it seems that my setup has quite the power draw. With an overclocked CPU, and the ATI 9600 Pro, the draw is fairly heavy. But, as it turns out, the Abit NF7-S is a power-hungry lil mobo. However, there is good news!

After talking with a representative from SilenX, the low 12V rails can be solved with a simple tweak of an included potentiometer, which is shown in the below picture. It can be turned with a cross head screwdriver, and turns up the power on that low rail. Thusly, you can tweak the PSU to give yourself a bit of a boost if the rail seems low to you. SilenX's calibration methods are as follows: "When we calibrate the PSUs, we do it under a full load so the voltages on a system that uses less load can ironically be lower (if there's no load placed on the PSU at all, the voltage will drop down even further)." So, in most cases the PSU should be fine - another plus for SilenX.