Despite the previously unprecedented performance of modern PC components, their real power consumption during a gaming load does not go beyond 300-400 watts. Naturally, if we are talking about quad-core processors and single-chip video cards. Considering that the power supply must be operated with a margin of about 25%, it becomes obvious to use a 400-550 watt device. For example, such as in this review — be quiet! Pure Power L8 400W.

be quiet! Pure Power L8 400W (BQ-L8-400W)

be quiet! Pure Power L8 400W (BQ-L8-400W)

The power supply in question comes in a black box with a corporate design inherent in a German company. The device has a «bronze» certificate and boasts an efficiency of up to 85% depending on the load.

be quiet! Pure Power L8 400W (BQ-L8-400W)be quiet! Pure Power L8 400W (BQ-L8-400W)

In addition to instructions and a network cable with a set of mounting screws, the delivery set contains a set of nylon ties that will allow you to carefully collect excess wires inside the system unit after assembly.

be quiet! Pure Power L8 400W (BQ-L8-400W)

All cables are an integral part of the power supply, and their number should be enough for an average PC:

  • one with a 24-pin motherboard power connector (47 cm);
  • one with 8-pin (4+4) CPU power connector (56 cm);
  • one with two 8-pin connectors for powering PCI-E video cards (53+15 cm);
  • two with two power connectors for SATA devices and two for IDE (46+15+15+15 cm);
  • one with two power connectors for SATA devices, one for IDE and one FDD (46+15+15+15 cm).
be quiet! Pure Power L8 400W (BQ-L8-400W)

The cables are nylon-sheathed, and the video card connectors are blue to avoid confusion with the EPS12V.

Externally, the Pure Power L8 400W model is no different from similar solutions, only the grille reveals that the product belongs to the be quiet! In depth, the block is almost 150 mm, which is a little strange, given the compactness of its internal filling, but more on that below.

be quiet! Pure Power L8 400W (BQ-L8-400W)

A gray ring is glued to the fan as a decorative element. At first it may seem that it is to minimize noise, for example, from air flow or reduce grille vibration, but alas, the ring is plastic. The older models of this line have an orange ring color.

be quiet! Pure Power L8 400W (BQ-L8-400W)

According to its characteristics, the unit meets modern requirements, when the entire load falls on +12 V. It can deliver up to 30 A for this voltage on two lines at once, or 22/20 A on each line separately. For a quad-core processor and a mid-range card, this is quite enough. Even with a little acceleration.

be quiet! Pure Power L8 400W (BQ-L8-400W)

The combined power for low-voltage lines is 120 W, for standby mode 3 A is provided, and for the -12V line — 0.3 A.

Power rail +3.3V +5V +12V1 +12V2 –12V +5Vsb
Max. load current, A 24 15 22 20 0,3 3
Combined power, W 120 360 3,6 15
Total maximum power, W 400

The unit has an active PFC and can operate from a wide range of mains voltages. Of the protections, the model is equipped with protection against current and power overload, overvoltage and undervoltage, against short circuits and overheating.

We remove the cover, and we see the HEC platform with group stabilization of output voltages.

be quiet! Pure Power L8 400W (BQ-L8-400W)be quiet! Pure Power L8 400W (BQ-L8-400W)

There is nothing reprehensible in the latter, since most of the blocks are made according to this scheme, and only more expensive solutions already have independent stabilization of each voltage.

be quiet! Pure Power L8 400W (BQ-L8-400W)

The unit is made soundly, there are no complaints about the assembly, all elements are present, even the input filter is made in full.

be quiet! Pure Power L8 400W (BQ-L8-400W)be quiet! Pure Power L8 400W (BQ-L8-400W)

From the control chips on the board, you can find a monitoring chip and a controller responsible for the standby voltage. The rest, apparently, are located on a separate scarf, which is protected by heat-shrink tubing.

be quiet! Pure Power L8 400W (BQ-L8-400W)be quiet! Pure Power L8 400W (BQ-L8-400W)

Three radiators with small fins at the ends are responsible for the favorable thermal conditions of the power elements: one for the diode bridge and the APFC module (pictured is the board with controllers), one for key transistors and one more for Schottky diodes. The latter has a fan rotation control board and a pair of thermal sensors.

All chains are equipped with Teapo and Taicon containers, not the most expensive option, but it is found quite often in well-known solutions. The high voltage part uses a 220uF capacitor with an operating voltage of 400V.

The quality of the soldering is also nothing to complain about, everything is well done, no complaints.

be quiet! Pure Power L8 400W (BQ-L8-400W)

The Silent Wings L8 T12025-MS-16 branded model with a threaded sleeve with a maximum speed of 1600 rpm and a two-wire connection is used as a fan.

be quiet! Pure Power L8 400W (BQ-L8-400W)

It works relatively quietly without any extraneous overtones.

Test Methodology

It is difficult to conduct a full test without an appropriate stand, so the power supply was tested using a conventional system assembled from the following components:

  • Processor: Intel Core i7-6700K (4.0@4.5/4.2 GHz);
  • motherboard: ASUS Maximus VIII Impact (Intel Z170);
  • Cooler: Prolimatech Megahalems;
  • RAM: HyperX HX430C15PB3K2/16 (2×8 GB, DDR4-3000, 15-16-16-35-1T);
  • video cards: NVIDIA GeForce GTX 780 Ti;
  • drive: Kingston SSDNow UV400 240GB (240 GB, SATA 6Gb/s).

Testing was carried out in the Windows 10 x64 environment on an open stand. To create the maximum load on the system, the LinX 0.6.5 and FurMark 1.17.0 utilities were simultaneously launched for 30 minutes, and the Valley benchmark acted as a gaming benchmark.

The Basetech Cost Control 3000 was used to measure the total power consumption of the system, also capable of displaying peak power, current, mains frequency, power factor, etc. on its LCD screen. possible efficiency of the device. Errors in such calculations can be 5%. The voltages were checked with a UNI-T UT70D digital multimeter.

In addition, we decided to slightly expand testing by taking temperature readings inside the power supply, fan speed and noise level under a particular load.

The temperature was measured using the Scythe Kaze Master Pro panel, the sensors of which were located on the radiators inside the block and at a distance of 1 cm in front of the fan (#1) and behind the outer wall (#2).

be quiet! Pure Power L8 400W (BQ-L8-400W)

For fan speed results, a UNI-T UT372 non-contact tachometer was used. The maximum speed was fixed for each of the power supply testing modes.

The noise level was measured with a UNI-T UT352 sound level meter in a typical quiet room at a distance of 1, 0.5, 0.1 and 0.01 m from the device under test. With the help of a speed controller and a tachometer, the fan speed was restored, corresponding to each mode of testing the power supply. Background noise did not exceed 33.4 dBA.

It should be borne in mind that such a technique at this stage is far from ideal and will be supplemented and changed as it is used.

Test results

The obtained data are entered in the table. In brackets for voltage are percent deviations from the norm, for power consumption — the approximate net load on the power supply.

GTX 780Ti GTX 780Ti GTX 780Ti
Mode Idle Burn, Game Burn, OCCT
Power consumption, W 46 (~37) 353 (~300) 460 (~375)
Line +3.3V, V 3,42 (+3,6) 3,4 (+3) 3,39 (+2,7)
Line +5V, V 5,06 (+1,2) 5,13 (+2,6) 5,12 (+2,4)
Line +12V1 (MB), V 12,12 (+1) 11,76 (–2) 11,72 (–2,3)
Line +12V2 (CPU), V 12,12 (+1) 11,82 (–1,5) 11,77 (–1,9)
Line +12V3 (VGA1), V 12,12 (+1) 11,69 (–2,6) 11,65 (–3)
Line +12V4 (VGA2), V 12,12 (+1) 11,7 (–2,5) 11,66 (–2,9)
Fan rotation speed, rpm 544 923 1102
Thermosensor No. 1 25,9 25,5 26,1
Thermosensor #2 26,5 27 28
Thermosensor No. 3 33,7 42,3 43,8
Thermosensor No. 4 34,8 42,5 43,4
Thermosensor No. 5 38 65,4 72,2

Like all more or less affordable power supplies, our ward at maximum load gave out a low voltage along the + 12V line, but did not go beyond 3%, which can be called a good result. Considering that the power supply will most likely be operated under a gaming load, the voltage drop will no longer be so large.


The reviewed be quiet! The 400W Pure Power L8 is an example of a classic product with budget-friendly features. But unlike them, this model boasts a good package and quiet fan operation. True, such wonderful properties are not given to the block for free — the user will have to pay 1.5 times more than for competitors. All in all, if you’re on a budget and want to build a relatively quiet mid-range gaming system, the Pure Power L8 400W is a solid choice.

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