NesteQ ASM Xzero series power supplies have some unique features that makes them ideal for everyone who wants a silent working environment. First of all it is a semi-passive power supply with heatpipe cooling system and a 12cm fan that is controlled and starts working only if the temperature inside the psu exceeds 65 degrees celcius!The fan can also be manualy adjusted at the speed we want.

It also has a power monitoring panel at the back that allows the user to check if everything is going ok at 3.3v,5v,12v and 5Vsf lines. Another strong point of the ASM Xzero series if the EECS (Enchanced Easy Connection System) that allows the user to combine cables and achive lengths that no other psu can offer.

Let's have a look at the features and specifications!

All data is taken from NesteQ website:

ASM (Advanced Silent Mode) technology contributes to develop a silent power supply. When the temperature within the power supply rises up to 65°C, an automatic fan regulation will be activated to adjust the fan speed (RPM) of the 120mm fan. NesteQ aims at presenting you a comfortable and quiet experience, even though your PC system is at full load. Only when the temperature rises to 65°C, the fan will spin for a short time to dissipate the heat.

The “Power Monitoring Panel” on each ASM Xzero power supply indicates if there are problems with the most important power output rails. If there should be a power failure on one of the +12V, +5V, +3.3V or +5Vsb rails, the green LED will be off. Included in the package is an adaptor, which can be plugged to test the power supply even without a mainboard.

You will experience a special flexibility(EECS) only with the ASM Xzero power supply series, when it comes to configuration of the useful cables. You can combine hard drive, floppy and Serial-ATA plugs freely, and those cables will be used only in real need, it goes without saying, in an unique way. You can use up to four cables to make one long cable. With other power supply units you can never have such a dream flexibility in cable management.

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.

The ASM Xzero 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.

• Highly efficient heat pipe cooling
• Active PFC (Power Factor Correction)
• Up to 89% Efficiency
• ATX12V Version 2.2
• EPS12V Version 2.91
• BTX Version 1.0a
• +12V Power - Plus Technology
• Advanced Silent Mode Technology
• Stack Effect Cooling Solution (SECS)
• Power Monitoring Panel
• Enhanced Easy Connecting System
• Over Power / Voltage / Current / Temperature protection
• Short Circuit Protection

Output Table

Cables Table

Scope of Supply: 1 x NesteQ ASM Xzero Power Supply, 1 x Power cord, 4 x Screws, 1 x Manual, 1 x EECS Cable Package (Extension cable, SATA Cable, 4Pin HDD Cable, FDD Cable), 10 x Cable ties

• Dimensions (width x length x height): 150 x 160 x 86 mm
• Automatic input voltage selection: 110 ~ 240VAC / 50 ~ 60Hz
• Fan dimensions (width x length x height) : 120 x 120 x 25 mm
• Fan bearing: Sleeve bearing
• Color: Matt black housing

Let's see the packaging!

The packaging is very nice and colorful. We can see some features like the heatpipe cooling and 105 degrees rated capacitor at the front.

The front piece can be opened and reveals a transparent window though which we can have a look at the psu.It also explains what is ASM(Advanced Silent Mode).

More down we can see what cables are included.

At the side there is an explanation of the Stack Effect which can improve cooling and increase the Fully passive state of the psu of up to 42%.

At the other side we can see what +12v Power Plus is, a patented technology which boosts 12v power in order to be able to support demanding components.

At the bottom we can see the technical specifications.

And at the back there are the rest of the features(ASM,Power Monitoring Panel,EECS) and an explanation for each one of them 

When we open the package we can notice the psu and 2 pieces of cardboard.

If we remove them we can see the cables and a bag that contains the modular cables and the accessories that are included.

Cables include 2x440mm Sata cables and 2x440mm 4-pin Molex cables.

Also included there are 2x500mm PCI-E 6+2P cables and 2 extension cables.

We also find a power cable,2 fdd cables,2 fan connection cables,some tie wraps,screws, caps for the extension sockets and a 24pin adapter to power the psu without connecting it to the pc.

All cables have the EECS system, this means that every cable has a connector at the end that allows us to extend the cable.The EECS connector is the one at the bottom.

Here is an extended cable.

If we don't use the EECS connector we can cover it with the included caps.

The included 24-pin cable adaptor is very useful if we want to test the psu without connecting it to a pc.

Also the psu has a fan speed signal cable(cable at the right) that allows us to monitor the psu fan speed.Also the 24 pin ATX cable has a very sufficient length for every case, even those that have the psu positioned at the bottom

Now let's have a closer look at NesteQ ASM Xzero 500w 

The NesteQ ASM Xzero 500w seems very nice, it has a beautiful matt black finish and golden fan protector.

We can notice the golden fan protector with the NesteQ logo in the middle and the 12cm fan.

From the front we can notice the hot air exhaust, the power switch and the ASM panel with the Power monitor panel.

The ASM mode can change with a gentle push of the golden knob.When it is in the manual mode we can adjust the fan speed by turning the knob.Also we can see the Power Monitoring Panel above the ASM panel. All leds have to be green, if anyone turns off it indicates that there is a problem with the specific line.

From the side there is a very nice ASM Xzero logo.

A sticker with the specifications is placed at the bottom of the psu.

At the front we can see the modular cable connectors.

Let's have a look at the inside!

NesteQ ASM Xzero 500w seems quite tidy from the inside, we immediately notice the heatpipe cooling system.

Transient filtering is very good, with an X-capacitor and 2 C-capacitors.It also has 2 ferrite rings and a very sufficient second stage filtering!

The fuse is in a protective material that will protect other components in case it blows.

The main capacitor was wrapped with heat tape, I unwrapped it but I wasn't able to find the manufacturer. So I contacted NesteQ and the capacitor is made by Nippon Chemicon and is rated at 105 degrees, a high quality capacitor!

Secondary capacitors are made by Teapo and rated at 105 degrees, high quality and reliable caps.

The cables restrict the airflow towards them and they might get pretty hot but NesteQ predicted this and used 105 degrees rated caps instead of 85 that most psus have at this wattage.

Here we can see the heatpipe aluminium fins

Everything is held securely into place with screws and glue to avoid any vibrations.

The heatpipes start from the mosfets and go to the fins. We can notice that thermal paste is used to achieve better thermal conductivity.

Internal build quality is good, but some things are simply glued wherever they would fit like this X-capacitor,I think a better topology would improve the reliability of the psu.But the heatpipe cooling system restricts things a lot so we cannot expect perfect topology in a so restricted space.

Here we can see the thermal sensors attached to the heatsink.

In this PCB we can see the fan control system that is used to adjust the fan speed.

Fan is made by ADDA which is known for the high quality fans. 

Let's see how the ASM control panel works!

When the NesteQ ASM Xzero is at the manual mode we can adjust the fan speed by turning the knob.The fan can be adjusted from ~1000 to ~2000rpm.

With a gentle push of the knob the ASM mode is activated, the Fan On led lights when the fan starts to spin. We can also see the power monitoring panel. If everything is ok all four leds have to be on, in case a rail fails the corresponding led will be off.

Power supply testing methodology

• For testing power supplies I am using a homemade tester that consists of multiple power resistors and amperometers.
• This allows me to control with pin point accuracy the exact load at each rail
• One more reason to test psu's with this method is that high power power supplies(800+ watts) are very difficult to be tested with a normal system.With the tester I am using I can achieve loads of up to 1800 watts.
• Readings are taken with a high sensitivity digital multimeter, and if required a voltage drop diagram is made.
• In order for a test to be considered successful the psu has to be able to perform it for 2 hours.
• Noise levels are recorded from 10cm away from the back of the psu(air exhaust) 

TESTING Part 1st (Real testing)

At this part the NesteQ ASM Xzero 500w will be tested in real conditions, in my pc that was built for this reason.

Testbed

• CPU:Intel core i7-950 @ stock speed
• Mobo:EVGA X58 Sli
• VGA:Dual MSI GTX 260@ Sli(Only one vga was used for this review)
• Memory:Adata 6Gb kit
• HDD: 4x Seagate 500Gb

This system is able to draw about 500w, so it will push the NesteQ ASM Xzero 500w to its limits.All reading were taken with a high sensitivity digital multimeter.In order to achive max load several instances of Orthos were running,with Furmark to stress the vga cards.Below we can see the results.

The NesteQ ASM Xzero 500w remained very silent at idle and most of the time the fan was not working, but at load the noise was higher and fan was working almost all the time but at low-mid speed.This is normal because a 500w psu is not intended for a computer like this and is really pushed to its limits.The psu had also some slight voltage drop, but it was normal and nothing to worry about.

TESTING Part 2nd(Synthetic testing)

At this part my homemade psu tester is used.This allows me to know the exact load of each rail.This is very usefull because I can measure the efficiency and also see if the psu can really provide the specified wattage.

Please note that synthetic testing is much more difficult for the power supply, and this means that it has more voltage drop than with the same load at a real system. 

Here are the results:

Part 1 - 30% load

Part 2 - 50% load

Part 3 - 80% load

Part 4 - 100% load

Part 5 - Individual line loads(each line is tested alone with the maximum specified load while the others has a load of 1A*)

*The 1A load was needed in order for the psu to work correctly.With load only to one line and others left without any load strange thinks were happening.....)

Efficiency

Efficiency is calculated by measuring the consumption of the power supply for known loads.

Temperatures

Here exhaust air temperature was measured with the psu in "Manual Fan speed control" mode and the fan in the lowest rpm(~1000).  

NesteQ ASM Xzero 500w was able to withstand 500w load for 2 hours, so I raised the bars and tried to find its absolute limits...For short time it also was able to hold with 610w load, but after about 30 minutes the psu was shutting off.The max load the psu was able to withstand without failing was 530 watts.The noise was very low at all times because of the automatic fan and the high efficiency cooling system with heatpipes. We can have a look at the fan and noise testing below.

Fan speed diagram

I monitored the mosfets heatsink temperature and the rpm of the fan at the ASM mode and recorded the values. While running this test I also tried to heat the psu as more as possible in order to find the temp where the psu shuts off. It did shut off by the overheat protection when the mosfet temperature reached 80 degrees. The point where fan started spinning was at 55 degrees at the measurement point (the temp of the heatsink near the temp sensors- Click here for image).

NesteQ ASM Xzero 500w Sound pressure level

Generated sound was monitored 10cm away of the exhaust of the psu at a sound insulated box in order to eliminate any external sound or echo.Readings are taken using a high sensitivity digital SPL meter.(Values under 17dBA are considered to be inaudible)

We can see that sound levels are very low when the fan works, but at full rpm noise generated is pretty intense. In fact the only way I found to successfully reach such high temps in order to record the fan speed was by heating the power supply with a hair dryer. In a real system I really doubt if the fan will exceed 1400rpm ever.

NesteQ once more produced a product which will attract many buyers because passive and semi-passive products are very rare to find and most of them are simply not good.The semi-passive idea is much better than a 100% passive since a power supply would never be able to stay cool without active cooling at some times. This is how ASM Xzero works, when it gets hot the fan starts until the temp drops, then it stops again. The fast transfer of the generated heat is done with two heatpipes that take away fast and effectively the heat.

Additional features like the power monitoring panel and the EECS cables are also very useful. The only bad thing about ASM Xzero 500w is the price...with an MSRP of 119 euros for 500w it can be considered very expensive. But passive and semi-passive computer parts have always been really expensive so this is not unusual.

I was also impressed with the high efficiency.To be honest I never expected the claimed "Up to 89% efficiency" to be truth...But it is! I measured up to 88% efficiency, while the efficiency graph always stayed above 82%. The ASM Xzero 500w also has very tight voltage regulation and all voltages are within ATX specifications even and at 100% load at the synthetic test where most power supplies suffer from severe voltage drop.

So...If you want a very stable and reliable semi-passive power supply with many features and high efficiency ASM Xzero series from NesteQ is for you!

Pros

• Nice looking
• Low noise
• The most advanced semi-passive psu in the market
• High efficiency at all loads
• High quality
• NesteQ patented cable extension system
• Power monitoring panel
• Rich bundle

Cons

• Price is high

"NesteQ ASM Xzero 500w is given the "Editors Choice" award for being one of the best semi-passive power supplies, and the "Green award" for its high efficiency...