Are be quiet! power supplies quiet? Half-load figures run from 6.5 up to 14.8 dB(A)

Half-load ranking, 6.5 to 14.8 dB(A)

Three Power Zone 2 sizes share the bottom spot. The 1200W follows at 7.7, then the Dark Power 14 850W at 7.9.

Half load means half the rating, so 375 W on a 750W unit and 500 W on a 1000W one. Since the Power Zone 2 figure does not move between 750W and 1000W, a heavy system can take the larger model and give up nothing at this row.

At 20% load the Pure Power 13 M passes the Dark Power

On a 750W unit, 20% is 150 W, the row to read for a PC that spends its day at light work.

The Power Zone 2 750W, 850W and 1000W lead again at 6.5 dB(A). Second is the Pure Power 13 M 750W at 7.2, below every Dark Power model on the sheets. After it come the Pure Power 13 M 650W at 7.3, 550W at 7.5 and 850W at 7.6, then the Power Zone 2 1200W and Dark Power 14 850W at 7.7, and the 1000W and 1200W Dark Power 14 at 8. The Dark Power Pro 14 IO reads 8.6 at 1300 W and 9.2 at 1600 W.

Further up sit the Pure Power 12 line, from 8.7 to 9.2, the System Power 11 U from 10.4 to 10.6, and the System Power 11 M from 12.9 to 14.8.

Which be quiet! power supply is quietest at full load?

It is the smallest Pure Power 13 M, the 550W, with 14 dB(A). Behind it are the Pure Power 12 550W at 14.6, the Power Zone 2 750W at 15.8, the Pure Power 13 M 650W at 15.9, the Dark Power 14 850W at 16 and the Pure Power 13 M 750W at 16.5.

Small units win this row for a simple reason. Each one moves less power at 100%, and a 550W model running flat out is drawing about what a 1000W model draws at 55%. Set the full-load row against your own peak draw, then, and not against the wattage on the box.

The top of the scale belongs to the System Power 11 U 750W at 35.3, the Pure Power 13 M 1200W at 32.3 and the System Power 11 U 650W at 32.2.

Bigger units list more at full load

Every series follows that rule except the Power Zone 2, whose 1200W reads 25.5 at full load against 27.2 for the 1000W.

The Pure Power 13 M shows it most clearly, climbing 14, 15.9, 16.5, 17.6 and 19.5 from 550W to 1000W before jumping to 32.3 at 1200W. Over the same five sizes the Pure Power 12 goes from 14.6 to 31.6. Half load barely moves by comparison: the Dark Power 14 shifts from 7.9 to 8.3 across its three sizes, and the Power Zone 2 holds still until 1200W. Nothing is printed between the four loads, so a PC drawing 400 W falls between rows on most of these units.

Does the fan stop on a be quiet! power supply?

At low load, yes, on the Power Zone 2, Pure Power 13 M, Dark Power 14 and Dark Power Pro 14 IO. No wattage is given for the point where the fan starts.

The Pure Power 13 M page puts it this way: "While under low load, the fan turns off completely until its services are needed again for more demanding operations." The Power Zone 2 is billed as "our first semi-passive power supply series".

Two flagships let you choose. The Dark Power 14 has "A button on the rear of the power supply" to switch between an always-on fan and semi-passive mode, and the Dark Power Pro 14 IO makes the same choice in be quiet!'s IO Center software. Neither sheet says which mode produced its dB(A) rows.

There is no semi-passive or zero-RPM claim on the Pure Power 12 page, whose 10% figures run from 8.6 to 9 dB(A).

How does be quiet! measure power supply noise?

At one meter. A separate volume and noise page states that "all measurements are made with a measuring distance of one meter", while the power supply tables carry only the load percentage, with no test standard, room level or fan mode beside the rows.

That same page argues that "a loud graphics card is no reason to neglect the volume factor when choosing a power supply". It is the best case for reading these rows at all.

A dB(A) figure at one meter is sound pressure, not sound power, and belongs beside figures of the same kind. Our sound power and sound pressure page sets out the difference, and the decibel ratings explainer covers comparing makers. Treat a gap of a few tenths between two units as noise in the test setup, since that setup is never described.

Small form factor units start at 12.4 dB(A)

At 50% load the SFX and TFX units list 12.4 to 14.5 dB(A), more than any Power Zone 2, Dark Power or Pure Power ATX unit at that row. They cool with 80 mm or 120 mm fans.

The SFX L Power reads lower at 20% than at 10%, 8.5 against 9.2. No other unit in the range does that.

Three slips on the spec sheets

Decimal commas turn up on one series: the Dark Power Pro 14 IO pages print every noise figure with a comma, "8,7" and "22,1" among them, where the rest of the range uses points.

Two pages put a number where a grade belongs. The Power Zone 2 750W and 1200W give "Cybenetics ETA" as "2", while the 850W and 1000W pages read Platinum, and the Dark Power 14 850W page showed "1" in that cell in September 2026 before reading Titanium on November 9. The third slip is the SFX L Power's 20% row sitting below its 10% row.

Series with no figure, or gone from the menu

Only the System Power 11 B prints nothing. Its 650W (BP014EU), 450W and 750W pages show "-" in all four dB(A) rows, and the B pages we found carry EU and UK article numbers only.

Three older series still have live pages with figures, though none appears in be quiet!'s power supply menu any more. The Dark Power 13 heading there now leads only to the two Dark Power Pro 13 models.

Retail stock can outlast these pages. Match the full model name before trusting a figure.

For other brands, see our power supply guide; be quiet!'s fans and coolers are in the be quiet! fan guide.