Pure Power L8 700W PSU Review Introduction

Be Quiet! is an European company which, despite the strange name, is a very well-known manufacturer  amongst enthusiasts, mostly for their high quality (and notoriously expensive) power supply units. We had an encounter with their very impressive Dark Power Pro 10 series a few months ago; however, impressive as it was, the price tag of such a power supply would certainly drive the vast majority of users away. Today we will be having a look at the least expensive PSU series currently offers, the Pure Power L8.

The Pure Power L8 series consists of both modular and classic power supply units ranging from 300W up to 730W. Even though the manufacturer boasts some very impressive features and performance figures, the retail price of the L8 series units remains quite high, especially considering that it is supposed to be a series designed with value in mind. Today we will be having a look at the most powerful classic power supply of the series, the Pure Power L8 700W.

 Pure Power L8 700W

Pure Power L8 700W major features and specifications

Continuous power (W)

700

Peak power (W)

750

Form factor ATX 12V

2.4

Form factor EPS 12V

2.92

Modular cable management

-

Special technology

-

Voltage (Vac)

100 - 240

Frequency (Hz)

50 - 60

Input current (A)

10 - 5

PFC

active

Power factor at 100% load

>0.97

Compliant to Intel Haswell C6/C7

YES

Compliant to Intel C6 mode

YES

Power consumption in standby (W)

<0.3

Average life time (h / 25°C)

100.000

Operating temperature up to (°C)

40

12 V Rails (Multi-Rail operation)

2

12 V Single Rail operation

-

Overclocking key

-

 

Output

+3.3V (A)

25

+5V (A)

20

+12V1 (A)

25

+12V2 (A)

30

+12V3 (A)

-

+12V4 (A)

-

+12V5 (A)

-

+12V6 (A)

-

-12V (A)

0.3

+5Vsb (A)

3

Max. combined current 12V (A)

70

Max. combined power 12V (W)

636

Max. combined power 3,3V + 5V (W)

150

Hold-up time (ms)

16

 

Unboxing the power supply

The box

Be Quiet! supplies the Pure Power L8 unit in a fairly large and strong cardboard box. The visual theme of the box is very dark, almost entirely black, with only a shady image of the power supply itself decorating the front.

The box (rear)

Be Quiet! printed a lot of information on the back of the box, from the list of features down to the length of each individual cable, making the packaging itself essentially a basic manual.

Bundled Items

Being a value-oriented product, the bundle of the Pure Power L8 reflects that as well. Inside the box we only found a basic manual, a power cable, four black mounting screws and a few cable ties.

 

External Design of the Be Quiet! Pure Power L8 700W

Pure Power L8 700W

Be Quiet! certainly placed a significant amount of effort on making the Pure Power L8 stand out of the crowd, despite it being a value-oriented product. The chassis has been sprayed with a matte black paint and the standard fan guard has been replaced with a parallel grid one, which is a characteristic of all Be Quiet!’s power supplies. At 150mm long, the chassis fully adheres to the ATX design guide size standards; however, the numerous cables at the rear of the power supply add a lot of bulk.

 Side panel

Instead of using stickers, Be Quiet! embossed their logo on the left side of the power supply chassis. There is no sticker or embossment revealing the power output or even the series of the power supply on this side of the unit. This side of the unit however will only be visible if the case has its PSU compartment upside-down or a windowed right side panel.

 Right Side Sticker

The sticker with the electrical specifications and certifications of this power supply has been placed on the right side of the chassis. This sticker will be visible through a windowed left side panel, if the window extends over the PSU compartment of course.

 Front side

The front side of the power supply is fairly standard and uninteresting. There is only the AC power plug, a standard on/off switch and a sticker with the company logo to be found. The rest of the surface has been perforated, for the warm air to escape towards the outside of the case. The rear side of the unit is just as uninteresting; as this is not a modular power supply, there is only a hole where the cables are coming out from.

A look inside the Be Quiet! Pure Power L8 700W

 The Silent Wings fan

Once again, despite it being a value-oriented product, Be Quiet! installed one of their Silent Wings fans inside the Pure Power L8. This fan features ribbed blades and a rifle bearing, which is not the same as the Silent Wings fans which are being used in their more advanced power supplies, as they feature FDB bearings. Be Quiet! claims that this fan will only generate 30.8dB(A) at maximum load.

 Unit Interior

HEC (also known as Compucase) is the OEM responsible for the creation of the Pure Power L8 700W power supply. HEC used to be a renowned manufacturer of low-cost units but has presented several very good mainstream layouts lately, trying to work their way up on the market. Although the design of the Pure Power L8 is not based on a cutting-edge technology layout, the assembly quality and soldering job is well above average, increasing the end quality of the product.

 Filtering Stage

The filtering stage begins on a small PCB soldered on the back of the AC receptacle and continues onto the main PCB. A total of four Y capacitors, two X capacitors, three filtering chokes and a MOV form the filtering stage.

 Primary Side

The single input rectifier has been placed on a dedicated heatsink, near the edge of the PCB. After the bridge, naturally, the APFC circuit starts, with a Teapo 470 uF / 400 V capacitor and a medium-sized choke being the passive components. The active components, two transistors and a diode, are bolted onto the main heatsink, along with the two inversion transistors, which form a half-bridge configuration.

 Secondary side

The secondary side of the power supply is rather simple as well. Six conversion transistors, two for each voltage line, generate the 12V, 5V and 3.3V lines of the power supply. The 5VSB line is generated by a secondary, dedicated small transformer. Group regulation is being used to balance the voltage lines, which is a method known to create problems if the voltage lines are greatly unbalanced, thus it would give the Pure Power L8 real trouble getting through a “Haswell approval” test. The capacitors at the secondary side of this power supply are supplied by Su’Scon and Teapo.

Test setup

The load
In order to be able to effectively and efficiently test any computer power supply unit, we developed and constructed our own proprietary testing station. Our testing station consists of a number of power resistors and small capacitors, which in turn are connected to a RS485 electronic relay array which allow our load to be controlled through computer software alone.
USB interface and connection panel
When accuracy and speed are of critical importance, a simple multimeter or voltage meter is not sufficient for the task. To ensure the quality of our testing, an USB laboratory interface is being used to continuously monitor and record the readings of all voltage lines simultaneously. For ripple measurements, an oscilloscope is necessary and we chose the USB Instruments Stingray, the most widely used oscilloscope amongst low voltage PSU engineers and testers.
Measurement instruments
For accurate testing and repeatable results, a stable power input is also required. Thus, we are providing power to our test samples through a 3kVA VARIAC which allows us to control the input voltage of our test samples and also perform efficiency tests under both 110V AC and 230V AC input. A Lutron DW-6091 is also being used, monitoring the input voltage, real and apparent power, power factor and amperage.
The software
A power supply testing procedure would not be complete without thermal and acoustics tests. For our acoustics tests we are using a SL-5868P digital sound level meter, placed 1 meter away from the unit (DIN standard). Two PT100 sensors and their respective displays are being used to monitor the ambient temperature and the exhaust temperature of the unit.
Complete test setup during trial run

 Testing results (Regulation & Ripple)

BQL8700tables

BQL8700V3BQL8700V5

BQL8700V12

Considering the league of the Pure Power L8 700 W power supply, the electrical performance of the unit is excellent. Ripple suppression is very good, especially while the load of the power supply is low to medium. Under heavy load, the voltage ripple nearly doubles, reaching up to 56 mV on the 12 V line; however, even then, these ripple figures are less than half of the 120 mV design limit. Voltage regulation is very good as well, at about 2% on the 5 V and 12 V lines and at 2.8% on the 3.3 V line.

Testing results (Efficiency, Noise & Thermal)

 BQL8700eff

The Pure Power L8 700 W power supply honors its 80Plus Bronze efficiency certification with ease. It managed to reach an efficiency of 87.5% at nominal load and with an input of 230 VAC, while the efficiency did not drop below 84.6% during our testing. Reducing the input voltage to 110 VAC drops the efficiency by about 0.8% across the entire load range.

 BQL8700noise

Be Quiet! power supply units, as the name suggests, usually are rather quiet. The Pure Power L8 700 W power supply is no exception, as the humming noise of the fan hardly is discernable while the load of the unit is less than 60%. At 70% load the humming sound of the fan becomes audible, with the noise continuously increasing as the load increases beyond this point; however, even at maximum load, the fan of the Pure Power L8 rarely becomes loud.

 BQL8700temp

As the power supply is optimized for low-noise operation, the thermal performance of the Pure Power L8 700 W is merely good. A significant temperature delta develops once the load exceeds 50% of the unit’s capacity, with the chassis of the power supply becoming warm. Nevertheless, this rise of temperatures is not excessive, considering that the power supply outputs 700 W at maximum load.

Pure Power L8 700W PSU Review Conclusion

 Be Quiet! power supplies are commonly known to be capable of high performance and for their high quality, therefore the results which we received from the testing of the Pure Power L8 700 W unit did not come as a surprise to us. Despite the relatively simple, basic design, HEC did a very good job on both the layout and the assembly of the Pure Power L8 power supply, with no weak joints or spots to be found. The choice of parts could have been better though, such as, for example, better capacitors, since Su’Scon and Teapo are considered to be mediocre suppliers, especially when their products are being used for primary roles, such as the main APFC capacitor of this power supply. However, the Pure Power L8 700 W unit also comes with a 3 year warranty, which should partially alleviate any concerns about quality.

Fan guard

In terms of performance, the Pure Power L8 700 W unit did better than we usually expect from a product designed with value in mind. The electrical performance of the power supply was very good, with great regulation and ripple suppression, while the electrical efficiency of the unit is quite high for an 80Plus Bronze design. It would be easy for HEC to upgrade the efficiency ratings of this design by implementing any relevant technology, such as DC to DC converters or a full-bridge configuration. Be Quiet! has optimized this unit for low-noise operation and the Silent Wings fan does a very good job at it; as a result however, the thermal performance is rather mediocre for a 700 W unit.

Aesthetics rarely are a serious factor in this segment of the market, yet Be Quiet! clearly made a serious effort to make the appearance of the Pure Power L8 unique. Admittedly, a good paint job, engraved logos and a fancy finger guard are not much, yet these were more than enough to make the Pure Power L8 stand out from the crowd. The largest aesthetic issue that users of the Pure Power L8 700 W unit will be facing is the bulk of the cables.

Pure Power L8 700W

The value-oriented power supply range of Be Quiet! has left us with mixed feelings. Although the Pure Power L8 700 W power supply performs surprisingly well for a budget-level unit, the retail price is significantly higher than that of several competitive products, a fact which will certainly have a strong negative impact on this unit’s sales.

Legit Bottom Line: The Be Quiet! Pure Power L8 700 W certainly is a very good product, well made and offering excellent performance. If the retail price however is not on par with other similar products at the time of its release, the newcomer into the US market will be facing impossible odds against competition.