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bequiet! Pure Power L8 400W Review

Rating: 8.0.

Today we are looking at the latest power supply from BeQuiet!, the Pure Power L8. We analyse the 400W model which features an ultra low noise SilentWings fan and 80 Plus Bronze certification. These designs can deliver around 90% of their total power on the +12V rail. The Pure Power 8 range features six safety circuits and Taiwanese capacitors with a product warranty covering three years.

The bequiet! Pure Power L8 range of power supplies are a new non modular series targeting the widest audience at the lowest possible price. Previous models in the family had a ‘CM’ moniker after the name, this stood for Cable Management which was basically a fancy way of saying ‘modular’.

The 400W model we are reviewing today has a recommended retail price of £47 inc vat and on paper should be an ideal partner for a low cost media center.

Dedicated gamers will probably be looking at the Pure Power L8 600W and 700W models, which are competitively priced at £67 and £76 respectively.

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  • Exceptionally quiet operation achieved through an array of careful optimizations, including use of a silence-optimized 120mm be quiet! fan with durable Rifle-Bearing-Technology.
  • 400 Watts of continuous power and stronger +12V rails provide massive power reserves for those times your PC really needs it all.
  • 80PLUS Bronze certification and up to 88% power conversion efficiency let you do more work with the same power and reduce your power bills.
  • Sleeved cable lengths for improved cooling and more attractive appearance.
  • Extensive compatibility with latest specifications, including energy-saving requirements of Intel C6/C7, ErP2013 and Energy Star 5.2 guidelines. Ready for Intel Haswell platform.
  • German product conception, design and quality control.


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bequiet! artwork is always simple, yet effective. The Pure Power L8 400W unit ships in a black box featuring a high resolution image of the unit and some specifications listed underneath.
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The main box is compartmentalised with the power supply itself protected in bubblewrap, underneath a little user manual. It would be more effective to protect the power supply inside foam as the supply chassis is directly pressing against the cardboard sides of the outer box.
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The company supply a regional specific power cable, some cable ties and the user manual.
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This is not a modular power supply, meaning all the cables are hardwired out of the chassis. All of the cables are sleeved (not the flat ribbon style), which may make routing a little more tricky.

Cable Connectors
MB 20+4 pin x1
CPU 4+4 pin x1
PCI E 8 pin (6 pin +2) x2
SATA x4
MOLEX x3
FDD (floppy) x1

For a 400W power supply we can’t fault the number of connectors on the Pure Power L8 400W unit. There are a total of five cables, and two PCI e 6+2 connectors to power a single high end graphics card. If you want to run more demanding SLI or Crossfire multi GPU systems, it would be advisable to aim a little higher up the range.

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The BeQuiet! Pure Power L8 400W is an attractively finished power supply which looks like any other bequiet! power supply we have reviewed in recent years. The paintwork is good, although it does attract finger prints easily enough.

It didn’t quite pass our ‘system builder stress test’, which involves us running the head of a Philips screwdriver down the side of the unit with little to moderate force. It didn’t completely remove the paint, but it did leave a noticeable scar. We do this to mirror possible rough handling during a system build.
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The more observant among you will notice that this range of power supplies has a different ‘trim’ around the fan underneath the grill. The bright orange trim has been replaced with a modest grey version. The 120mm SilentWings fan can be seen underneath … we will look at this closer when we open the case.
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The panel sides have an bevelled company logo visible, subtle enough to be missed if you aren’t paying attention.
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All of the cables are hardwired into the chassis, shown above.
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One side of the chassis has a honeycomb vent in place to help with airflow. Next to this is a company logo in the white/orange colour scheme and a power switch and connector.
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BeQuiet! Pure Power L8 400W
DC Output
+3.3V
+5V
+12V1 +12V2
-12V
+5Vsb
Max Output
24A
15A
22A 20A
0.3A
3A
Total Power 120W 30A – 360W 3.6W 15W
400W

The power supply can deliver a total of 30A on the +12V rails, or 360W.

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BeQuiet! don’t use the same model of fan in their power supplies, each unit incorporates a fan specific for the power output, to ensure the lowest possible noise levels while maintaining a safe thermal curve under load.

The Pure Power L8 400W features the BQT T12025-MS-16 fan which operates at a maximum speed of 1,600 rpm. This 12V, 2.4W fan can push a maximum of 46.65 CFM. This 120mm fan has a specially finished surface texture to reduce air turbulences.

BeQuiet! say that every fan blade in their units is individually checked for micro unbalancing. If the need arises, each blade is tared out with tiny weighs to ensure balanced, lower noise performance.
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The BeQuiet! Pure Power L8 is a cleanly designed power supply with several rows of black painted heatsinks in place to aid with cooling proficiency. This design topology is a Double Forward implementation, used for cost efficiency.
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The soldering quality inside this supply is quite clean throughout.
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This unit is using a mixture of Teapo capacitors, with the primary capacitor rated 420V, 220uF @ 85C. We wouldn’t expect to see a 105C primary stage capacitor in a budget oriented model such as this, although some of the secondary capacitors are 105c rated. This will help long term as they are predominately bunched in airflow restricted areas of the PCB, close to the hardwired cables. The Pure Power unit offers OCP, OPP, OVP, UVP and SCP and Over Temperature Protection (OTP) for both +12V rails. The IC is located on a separate PCB which means the design has more space to accommodate bigger transforming components.

Behind the AC receptacle is a small PCB which is home to some of the transient filtering stage components. There is also the ‘on/off switch’ here.

The supply is using a modularised EMI solution board. The EMI stage is soldered into a separate PCB. BeQuiet! claim this unit achieves ErP 2013 standards with a power drain of 0.15W when in standby (it needs to be 0.25W or less for this certification).
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The cables are fully sleeved into the chassis and tied into place for added security. There is a rubber grommet around the metal as well, to ensure long term fraying is not a concern.

On this page we present some super high resolution images of the product taken with the 24.5MP Nikon D3X camera and 24-70mm ED lens. These will take much longer to open due to the dimensions, especially on slower connections. If you use these pictures on another site or publication, please credit Kitguru.net as the owner/source.
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Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)• Variable Autotransformer, 1.4 KVA

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
80W
1.57
3.34
1.81
5.05
4.83
12.11
1.00
5.02
0.20 -12.03
200W
2.85
3.31
3.62
5.03
13.65
12.00
1.00
5.01
0.30 -12.03
300W
4.94
3.31
5.68
5.02
20.50
11.94
1.50
5.01
0.30 -12.04
400W
3.98
3.26
4.66
4.99
29.32
11.88
2.00
5.00
0.50 -12.04
BeQuiet! Pure Power L8 400W Maximum Load
462W

We pulled 462watts from the unit before it shut down. The overcircuit protection system worked fine and it shut off safely. Load regulation seems reasonably good, and nothing troublesome was documented.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing +3.3V +5V +12V -12V +5VSB
A V A V A V A V A V
385W 2.0 3.31 2.0 5.04 30.0 11.87 0.20 -12.04 0.50 4.99
170W 18.0 3.23 12.0 4.95 4.0 12.10 0.20 -12.03 0.50 4.98

We have seen better results in our Crossloading tests, however the results don’t cause concern.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum. ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output
Ripple (mV p-p)
+3.3V
50
+5V
50
+12V1
120
+12V2
120
-12V
120
+5VSB
50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load +3.3V +5V +12V 5VSB
80W 5 10 10 5
200W 10 15 15 10
300W 20 15 30 15
400W 25 20 45 15

Ripple results are very good, with all rails falling well within the rated tolerance levels.

Efficiency (%)
80W
84.42
200W
88.46
300W
87.45
400W
86.10

The supply reaches over 88% efficiency at 50 percent load, and this falls to just above 86% efficiency at full load. Good results for a 80 Plus Bronze certified product.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the Power Supply we have taken it into our acoustics room environment and have set our SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refridgerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
80W
<28.0
200W
<28.0
300W
<28.0
400W
30.4

The BeQuiet! Pure Power L8 400W is barely audible at all, even under load. We really do love the SilentWings fans, they are some of the best fans that money can buy. The BQT T12025-MS-16 fan in this unit spins very slowly, even at full load.

Temperature (c)
Intake
Exhaust
80W
35
37
200W
38
44
300W
43
49
400W
47
58

The large SilentWings fan helps to generate high levels of airflow across the components inside the chassis, with 11c above ambient recorded at full load.

Maximum load
Efficiency
462W
84.9

Pushing the PSU above its rated limits generates an efficiency level of around 84.9%. This is not a viable ‘real world’ situation, but its interesting nonetheless.
The bequiet! Pure Power L8 400W power supply is an excellent little power supply, exceptionally well built and set to be sold at a competitive price point of around £40 inc vat. This will surely target those users with low to mid range single graphics cards or the audience who want a quiet power supply for a media center.

Technically the unit is unremarkable but it doesn’t exhibit any particular weaknesses. It delivers very good efficiency results for an 80 Plus Bronze certified supply and the ripple suppression is solid on all rails.

Aesthetically, we always like bequiet! product designs … they also opt for subtle black boxes with orange and white accenting which looks elegant in a shop window.

The latest non modular range have a noticeable change over the CM (Cable Management – or modular) models within the Pure Power L8 series. The fan trim has changed from bright orange to a dull grey. This means you can immediately tell whether the unit is modular or not, by simply looking at the fan grill section of the chassis. It sounds a minor point to make, but it is effective.

While this particular unit is not modular, the quality of the cabling is excellent although bequiet! have opted for traditional sleeved cables rather than the ‘easier to route’ flat ribbon style which many manufacturers are adopting with their latest models.

There aren’t a plethora of cables hardwired to the 400W unit, so unless your chassis has a terrible cable management system, they should be easy enough to hide out of sight.

Under £50 bequiet! face some competition from their own Pure Power L8 CM 430W power supply, which has recently seen some price cuts in the United Kingdom. Amazon for instance are selling the CM 430W for £50 inc vat, meaning it is only £10 more expensive than this non modular version we reviewed today.

For those people building inside a diminutive, physically restricted chassis, the non modular supply may make more sense, especially with such a minor price premium.

Pros:

  • Excellent all round performance.
  • exceptionally quiet.
  • looks nice.
  • competitive pricing.

Cons:

  • non modular.
  • the bequiet Pure Power L8 CM 430W (modular) model is only £3 more expensive in the UK today.

Kitguru says: A very capable little power supply targeting the budget audience.
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