Comparison be quiet! Pure Power 11 CM BN298 vs be quiet! Pure Power 11 BN294

The cable system used in the power supply. According to this parameter, modular, semi- modular and non-modular devices are distinguished, here are their features:

— Not modular. The classic version of the design, used in computer power supplies from the very beginning and not losing popularity to this day. The wires in such systems have a non-detachable design, and additional cables are not provided for connection. As a result, the user has to deal with only those cables that the manufacturer provided, without the ability to remove or replace them (the only modifications available are the installation of additional accessories such as an extension cord or splitter). Because of this, such PSUs are less convenient than modular and semi-modular ones: their wires are often excessively long, and some of them are not used at all, while such an “economy” further clutters up the case, worsening air circulation and cooling efficiency. On the other hand, these shortcomings can be reduced to almost zero with careful selection of the PSU and careful wiring; and non-modular systems themselves are distinguished by reliability and at the same time low cost. It is because of these features that they are most common nowadays.

— Modular. Systems in which each cable is made detachable; special sockets are used for fastening wires. Thanks to this design, you can optimally organize the space inside the PC —...for example, remove unnecessary wires so that they do not interfere with air circulation in the system unit; replace a cable that is too long with a shorter wire (or vice versa); swap cables, etc. At the same time, modular systems are noticeably more expensive than non-modular ones, while they are considered somewhat less reliable due to the presence of "weak points" in the form of removable cable mounts.

— Semi-modular. A kind of compromise between the options described above: some of the wires in such power supplies are made non-removable, some are equipped with modular mounts. This makes it possible to partially combine the advantages and compensate for the disadvantages of the two systems: semi-modular PSUs are less expensive and more reliable than modular ones, and at the same time more convenient than non-modular ones. Usually, in systems of this type, the most important wires have a non-removable design, which are almost guaranteed to be used when assembling a PC, and secondary cables are equipped with removable mounts and can be removed if not needed. However, the specific features of a semi-modular PSU should be specified separately.

Protection schemes provided in the power supply unit. In addition to the aforementioned OVP (Over Voltage Protection), OPP (Over Power Protection), and SCP (Short Circuit Protection), modern PSUs may include the following safety functions:

— OCP. OCP in power supplies monitors the current on power lines and shuts down the PSU if consumption becomes dangerously high, to prevent overheating wires, connectors, and power elements inside the unit, and to avoid affecting components. Unlike OPP, which triggers based on the total power of the whole unit, OCP often catches a localized issue on a specific line or group of outputs. Compared to SCP, it's an "earlier" protection: it reacts before a full short circuit forms when resistance is not zero but current is already risky. Real-life examples include an unsuccessful graphics card overclock, a damaged GPU power cable, or the rare but unpleasant case of connector bending/melting: OCP will shut down the unit faster than you'll notice the smell of plastic.

— UVP. UVP monitors the voltage drop on the power supply's outputs and shuts it down when the values become too low for stable operation to avoid freezes, data writing errors, and "half-dead" modes, which are especially unpleasant for the motherboard and drives. Paired with OVP, these protections work like "frames": OVP catches dangerous spikes, UVP catches dangerous drops, while SIP often tries to smooth out the power issue at the input. A typical ex...ample would be an overloaded weak PSU, poor grid, or turning on powerful appliances at home: instead of unstable operation and strange reboots, UVP prefers to shut down the system predictably.

— OTP. OTP monitors the temperature inside the power supply and shuts it down when the heat becomes critical, protecting the transformer, power switches, and capacitors from accelerated wear and accidents. This is a "harsher" safety net than AFC: automatic fan control tries to prevent overheating, while OTP kicks in when cooling no longer suffices— for example, if the case is clogged with dust, the fan stops, the PSU is in a cramped compartment, or the PC runs under heavy load for a long time in summer. In real life, OTP often saves the day when a user inadvertently blocks the air intake or the fan starts failing: instead of smoke and component degradation, the unit simply turns off.

— SIP. SIP in power supplies is designed for "dirty" power conditions: transient surges, drops, and inrush currents that occur when a fridge compressor, pump, or air conditioner starts up at home, or when the network is unstable. Conceptually, it aligns closer to smoothing out input problems than to OVP/UVP, which already monitor the output and simply shut down the PSU at dangerous values; SIP aims to enhance system resilience to everyday voltage drops and spikes but does not replace a full external stabilizer or robust power protection if the grid is truly bad. A typical example would be a private house or old housing stock: SIP helps endure minor network "nudges" without sudden reboots.

— NLO (No-Load Operation). The ability of a power supply to correctly start and operate even with zero or very low load on the outputs, without "floating" voltages and instability. Unlike protections like OVP/OCP/SCP that respond to emergencies (overvoltage, overload, short circuit) and often shut down the PSU, NLO focuses on stability when consumption is minimal, or the load is temporarily absent, reducing the risk of odd malfunctions during testing or in energy-saving scenarios. In practice, NLO is useful when testing the unit on a bench without a connected PC, when the system starts with a minimal set of components, and when the computer spends most of the time idling, reducing consumption to a "trivial" level.

— AFC. AFC in power supplies manages fan speed based on temperature and load: it rotates slower and quieter when idle, and speeds up as consumption increases to dissipate heat in time. This is not "emergency" protection like OTP, which shuts down the unit during overheating, but a preventative measure: AFC helps maintain temperature at a normal level, thereby indirectly prolonging the lifespan of PSU components. A real-life example is that at night, in a quiet room, the PC doesn't hum under low load, and during gaming, the cooling automatically intensifies, preventing OTP from triggering.

The noise level produced by the power supply.

Usually, the characteristics indicate the average value of the noise level during normal operation. The lower this value, the quieter the power supply and the more comfortable it is to use. However, it is worth noting that modern computer PSUs produce very little noise. So, in the quietest models, this figure does not exceed 20 dB — this is no louder than the rustling of leaves in a light breeze, such a sound is almost inaudible and is quite acceptable even in a residential area at night. Also acceptable for this application are noise sources of 21 – 25 dB(corresponding to a whisper at a distance of about 1 m) and 26 – 30 dB(wall clock ticking). Noise of more than 30 dB is already considered quite significant for computer PSUs; according to sanitary standards, such equipment in residential premises can only be used during the day.

When choosing a power supply for this indicator, it is worth considering a few points. First, noise reduction comes at a cost: it can affect the cooling performance and/or cost of the device. Secondly, the noise from the power supply is often lost against the background of louder PC components — for example, powerful cooling systems for the CPU or graphics card. Thirdly, the very environment where the PC is installed can be noisy — an example is a...n office or coworking. Thus, specifically looking for a low-noise model makes sense mainly in cases where maximum silence is crucial for you.

PC PSU dimensions are defined by the form factor (most often ATX 150×86 mm), and the key factor in compatibility is depth — the PSU case length. “Universal” ATX units are usually 140, 150 mm, while quiet, high-power models with large heatsinks and a 135/140‑mm fan range from 160 to 200+ mm; compact builds use SFX/SFX-L (depth ~100 and ~125 mm with an adapter bracket). The greater the depth, the higher the risk of hitting drive cages, the PSU shroud, cable management, or a front LCS radiator, and modular connectors plus cable bend radius require another 20 – 40 mm of real clearance.