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ASM X-Zero 700W Heat-piped Cooled Semi-Fanless PSU
(4 reviews)
ASM X-Zero 600W Heat-piped Cooled Semi-Fanless PSU
(5 reviews)
ASM X-Zero 500W Heat-piped Cooled Semi-Fanless PSU
(4 customer ratings / 4 reviews)
ASM X-Zero 400W Heat-piped Cooled Semi-Fanless PSU

Nesteq ASM X-Zero Heat-piped Cooled Semi-Fanless Power Supplies

- Replaces the Nesteq Semi-Fanless ASM PSUs

Nesteq's X-Zero power supplies offer minimum possible running noise along with market-leading quality, 3 year warranty and the convenience of their EECS modular connection system.

Nesteq's X-Zero power supplies offer minimum possible running noise along with market-leading quality, three year warranty and the convenience of their EECS modular connection system. Each PSUs also features a built-in PSU tester so you can easily diagnose any problems. It also has heat-pipe cooling to help achieve a cooler running PSU.

0dB(A) Semi-Passive - Advanced Silent Mode (ASM)

ASM technology has enabled Nesteq to develop a silent power supply. When the temperature within the power supply rises above 65C, an automatic fan regulator is activated to adjust the fan speed (RPM) of the 120mm fan. Nesteq aims to provide a comfortable and quiet computing experience, even if the PC is running at full load. Only when the temperature rises above 65C, will the fan spin for a short time to dissipate the heat.

One Step Check - Power Monitoring Panel

The "Power Monitoring Panel" on each ASM X-Zero power supply indicates if there are problems with the most important power output rails. If there is a power failure on one of the +12V, +5V, +3.3V or +5V sb rails, the green LED will turn off.

Enhanced Easy Connection System

EECS, short for Enhanced Easy Connection System, is the next evolution of the modular power supply. Just like an "ordinary" modular PSU, the PSU has sockets rather than fixed wires for powering the components installed in your PC. So what makes a modular PSU so great is that you only need to connect the cables that you require for powering the system. However, Nesteq's EECS PSUs take this one step further by allowing you to connect different power connectors on the same cable rather than using two separate cables. For example, the image below shows one cable from the EECS PSU supplying power to two 4-pin Molex, two SATA and one floppy device. A non-EECS modular PSU would require at least two cables to provide power to these devices. This feature further reduces the amount of cables used inside the system, which makes things nice and tidy!

Reverse Install Possible - Stack Effect Cooling Solution

By turning the power supply unit upside down (fan facing upwards), the created low pressure can draw cold air from outside to enhance the passive cooling effect up to 42% at 0dB(A) ASM-mode. This leads to even less fan operation and a prolonged period of absolute silence.

+12V Power Plus Connection

The ASM X-Zero power supply series applies the patented +12V Power-Plus technology. This revolutionary technology makes it possible to supply the most important components (mainboard, graphics card) with a particularly resilient power source.

The X-Zero features heat-pipe cooling for a cooler PSU!
The X-Zero features heat-pipe cooling for a cooler PSU!


  1. Highly efficient heat pipe cooling
  2. Active PFC (Power Factor Correction)
  3. Up to 89% Efficiency
  4. ATX12V Version 2.2, EPS12V Version 2.91
  5. +12V Power - Plus Technology
  6. Advanced Silent Mode (ASM) Technology
  7. Stack Effect Cooling Solution (SECS)
  8. Power Monitoring Panel
  9. Enhanced Easy Connecting System (EECS)

SpecificationsX-Zero 400WX-Zero 500WX-Zero 600WX-Zero 700W
Model numberXZ-400 XZ-500 XZ-600 XZ-700
ATX12V Version2.2
EPS12V Version2.91
+3.3V maximum output current24 A
+5V maximum output current20 A 24 A 20 A
+12V1 maximum output current18 A 20 A 25 A 20 A
+12V2 maximum output current18 A 20 A 25 A 20 A
+12V3 maximum output current18 A 20 A 25 A 20 A
+12V4 maximum output current18 A 20 A 25 A 20 A
+12V5 maximum output current- 20 A
+12V6 maximum output current- 20 A
+5VSB maximum standby current2.5 A
Combined maximum output +12V324 W 420 W 504 W 660 W
Combined maximum output +3.3V / +5V120 W 130 W 140 W 150 W
20+4 pin ATX connectorYes
ATX12V 4-pin supportYes
EPS12V 8-pin supportYes
PCI-E support (6+2 pin)Yes (x2)
SATA connectors4 6
Number of hard drive connectors4 6
Number of floppy drive connectors2
Fan connection cable 1 x 5V and 1 x 12V (both can power 3 fans each)
PSU Fan speed monitorYes
Fan speed controlAutomatic, manual or semi-passive
Acoustic noise levelFrom 0dB(A) to a Max of 28 db(A) in extreme conditions
Dimensions86 x 150 x 160 mm (HxWxD)
Power Factor CorrectionActive PFC
Mains input voltage110-240 VAC, 50-60 Hz
Mains input voltage selectionAuto
Over voltage protectionYes, on all outputs
Short circuit protectionYes, on all outputs
Safety approvalsRoHS, CE, TUV, FCC
Master power on/off switchYes
Length of motherboard power cable60 cm (approx)
Warranty36 months
EAN barcode3246436782012 3246436782029 3246436782036 3246436782043

Customer Reviews

X-Zero 700W
X-Zero 600W
X-Zero 500W
X-Zero 400W

absolutely silent PSU for PC case with good ventilation


Originally fitted this product in a Dell studio mini tower PC for graphics card upgrade. I have never been able to trip the fan into spinning under ASM mode. However, my Dell case does not have sufficient ventilation when the PSU fan is off. I switched the mode from ASM to manual and turned the speed dial to the minimum setting. The PSU fan was still quite noisy (hence knocking off 1 star). After changing the case to one with better ventilation, I have been able to leave the PSU running in ASM all the time. Like other reviewers, I also hope the SATA pwr cables are a bit longer. They are barely long enough to reach the drives in my Zalman Z9+ case. Still, a great product overall.

Pros: absolute silent operation in ASM mode
Cons: noisy fan in manual mode (although very unlikely you'll need it)

Very impressive


I was a bit cautious about spending this much money on a PSU, especially one that claimed to be totally silent because the fan wasn't needed! But I tried it, and this PSU has done everything it claimed. Power is smooth, my system is more stable, and that fan honestly never spins. When I first installed it, I turned the switch to manual and the fan started. I set it to automatic, and it hasn't stirred since. I often set up large 3D renders and leave the PC running at 100% capacity for several days at a time (Quad Core Q9550, 8GB RAM, nVidia GTX460 2GB, 2 x 1TB HDD, Vista 64-bit OS) and I've never had a problem.

The only thing I would note is that if you have a case with a bottom-mounted PSU (I have a Fractal R3) they recommend mounting the unit upside down so the fan is on the bottom and draws in cool air (stack cooling). This is completely unnecessary as the fan never turns! Install it whichever way up is easiest for you.

Not a gimmick!


Was running a Jeantech 700w which did the job but kept my brother awake with the constant humm echoing through the floor/walls at night when rendering video from the fan constantly running even on computer standby. I was looking for a silent fan PSU and came across this Nesteq ASM X-Zero, with the ability to use the fan only when required. Great. I'm still amazed, the fan hasn't come on at all, not even under bench marking, gaming or rendering video.

Pro's: Bad voltage warning lights, over ride button for fan (you won't need this), Molex cables, absolute silent.

Con: Short molex cables (extenders included). I only say this because my HDD's are set at the bottom of my full size ATX case and now have two 4 pin connectors just hanging there. But then again I'm very fussy.

Very impressed and very happy. And I'm very fussy. Says it all.

0 db ! Great PSU.


The fan stays off all the time, even when I play games. So it probably needs even more load? ;) I have C2D E8400 with 260GTX. Never heard it autostart. Note that you have to push the button to switch to ASM mode (blue led). With fan on, is rather loud at full speed, but you can adjust the fan speed. Anyway it seems it doesn't need the fan with my system.

I got the Fractal Design case which isn't very ventilated. PSU stays on the bottom, fan facing upwards, like they recommend

This is a modular PSU. I didn't notice this when ordering. (maybe I didn't read carefully...)

Cons: ATX cables are rather short. Wouldn't mind an extra SATA cable. Expensive.

ASM fan quieter than manual fan


I have managed to trip the fan into spinning despite having a well ventilated case. But then it is nearly June and I live in a poorly insulated loft conversion. Although I will agree that the fan is fairly noisy under even the minimum setting on manual mode; under the ASM mode it seems lower fan speeds are permitted so it remains quieter than my CPU fan (also bought from QuietPC), hard disks are now the noisiest components. The only way I could tell that the fan was turning was because of the red light on the back of the PSU. The only real issue I have is how bright the blue ASM light on the back is, that was quickly remedied with an old train ticket and some sellotape. Oh yeah, and the price....

Buy It


Hello, this is my first review or feedback. I purchased one Zero 600W to see if it will do what it says on the description notes. I am very pleased to support and recommend this PSU because it never fired the fan while I used it. I am an architect and I do rendering for 3~6 days nonstop at times and during the summer time in August this PSU never made a noise.

I am not paid by quiet PC nor by Germans who made this unique unit. I hope this will help new buyers. It's pricey but buy it instead of buying one then buying another.

Worth every penny!


My old Akasa psu sounded like it was about to take off sometimes so when I read about this fanless psu I was eager to give it a try. I was a little dubious as I hadn't heard of Nesteq before but on checking the internet I saw it had many great reviews. This really is silent in ASM mode....I've only used it a few days but the fan hasn't spun even once! Build quality is great and there are some great little extras in the box. If you want a truly silent psu this is the one to go for. It's a little expensive but with a 3 year warranty you really can't go wrong. 10/10.

Worth the expense?


Definitely more pricey than others I looked at but enjoy peace and quiet which you definitely get! Quite strange when you turn on the PC for the first time and no noise whatsoever. Have only turned on the fan manually and is surprisingly loud so am hoping it isn't needed too often. Cables are a good design but each one has two connectors (sata or otherwise) and a plug to daisy chain a second cable. Great feature if you need them but if you only want to supply one device then the other connectors are left dangling. Wasn't a sata cable long enough to reach the DVD writer but included extension cable soon fixed that. A nice feature missing that some other PSUs have is the ability to control external fans based on CPU load. This and the price are the only reasons I have marked it down.

Well worth the price...


Used this little baby to replace my Corsair TX750 and with the setup that I have, the fan on this PSU doesn't even turn on when I did a stress test using Prime95 for 3 hours straight!

Bear in mind though, you will need good air circulation inside your case, otherwise there is no point in buying an expensive semi fanless PSU because the fan will then be turning on and off constantly as the heat build-up inside the case raises the temperature of the PSU!

My system is fitted with very silent fans and I'm going to buy a couple more from QuietPc.

The problem with PSU fans is that unless you know how to, it can be very difficult to replace the fan.

That is the reason I went for a semi fanless PSU as I know my system would never push it enough to make the fans come on.

My setup is: Lian Li Armoursuit PC-P60 Case, Core 2 Quad Q9550, Nvidia GTX 260, 2 HDD's, 4GB RAM, Arctic Cooler Freezer 7 Pro V2.

So get it if you already have a quiet setup which runs cool. 10/10

Great PSU, shame about the packaging


The product is excellent. I am loading it lightly (not a gamer) and the fan never runs. The case is neat inside, thanks to modular cabling, which probably helps airflow.

However, the manufacturers should be ashamed of themselves for the extravagant and unnecessary packaging. The box has folding panels, colour printing and a transparent window. The cables come in a zip fastening nylon bag. All of these were in the bin by the time the PSU was actually powering my PC! This strikes me as being an irresponsible use of resources for what is a workaday, internal component.

The ultimate PSU if you need low or no noise


Purchased for a client that records studio music via a PC and needed the lowest system noise possible. This product is unequalled when it comes to noise and can be set to 'fan off' allowing the inbuilt heatpipes to expel surplus heat (suitable for PC's set to a low performance).

Installation is easy due to the standard dimensions, air is drawn in through the fan grill and exits out the External power supply side. Ideally configure it to draw fresh air in, rather than the internal air in the PC. The LED's displaying condition are a wish come true for failure diagnosis.

It's such an excellent product that I will be investing in one for my own use (the 700w version).

Plenty of cable accessories for all conditions.

Quick delivery from quietpc as I've come to expect.

Ordering my second now


Knocked out by just how good this is. Setting up a new PC, thought I had a problem with the mobo or power supply as no noise when I pushed start. Yes, they're expensive, but without this, I can hear my PC humming throughout the house.

Nesteq ASM X-Zero 500W Semi-Fanless PSU


Was just about to give this PSU a duff report compared to my old Antec Phantom 500 as it appeared a lot noisier. Then noticed in the instructions you had to press the button IN. The silence is wonderful and I am happy again. 9/10 It was little pricey.

We haven't received any reviews of this product yet.


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