The power supply unit (PSU) is the backbone of your PC’s reliability, directly influencing system stability and longevity. Choosing the right PSU is essential, requiring careful consideration of objective metrics, such as wattage and performance, and subjective factors, like design and modularity. This selection process demands an informed understanding of your system’s power needs. While this may seem daunting, the following guide will provide clarity.
A high-quality PSU must include protective features that safeguard not only the power supply itself but also the other components in your system. If a PSU lacks these protections, it cannot be considered the best choice, as it exposes your valuable hardware to potential harm from power irregularities.
The Best Power Supplies You Can Buy Today
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Up to 650 Watts
The XPG Core Reactor II is priced at around $80, offering great value for its high efficiency, exceeding 80Plus Gold standards and achieving a Platinum Cybenetics certification. Manufactured by Channel-Well Technologies, it boasts solid construction and a 10-year warranty. Voltage regulation is excellent, though ripple suppression on the 3.3V and 5V lines is moderate. It is very well thermally balanced, generating no to very little noise unless heavily loaded. Overall, it is a strong choice for gamers and workstation builders seeking next-gen compatibility at a reasonable price.
MORE: XPG Core Reactor II Review
Up to 750 Watts
The Be quiet! Pure Power 12 M 750W PSU offers a reliable and well-constructed power supply option with an emphasis on stability, solid performance, and long-term durability, thanks to its dependable HEC/Compucase design and 10-year warranty. It features stable voltage regulation and effective ripple control, meeting its 80Plus Gold rating without exceeding it. The unit balances low noise levels during typical use, but under heavier loads, its acoustics worsen, reflecting a trade-off between quiet operation and thermal management.
MORE: Be Quiet Straight Power 12 750W PSU Review
Up to 1000 Watts
The be quiet! Dark Power 13 1000W PSU is a premium offering built on an excellent FSP platform, delivering top-tier performance and efficiency. Both CLEAResult and Cybenetics certify it as Titanium, showcasing its exceptional electrical efficiency. This PSU excels in power quality, ensuring stable and clean output while maintaining impressively low noise levels under any load. Priced at $270, it is a solid deal for a 1000W Titanium-certified unit, but with frequent discounts dropping it to $220, it becomes unbeatable in its class, making it a top choice for high-performance gaming or workstation builds.
MORE: be quiet! Dark Power 13 1300W Review
Up to 1200 Watts
The ENERMAX PlatiGemini 1200W PSU is a high-quality power supply designed for top-tier gaming and workstation PCs. Priced at $250, it offers impressive build quality, using premium components from manufacturers like Rubycon and Nichicon, and comes with a robust 10-year warranty. It meets ATX 3.1 and ATX12VO standards, delivering excellent efficiency with 80Plus & Cybenetics Platinum certifications, achieving up to 93.2% average efficiency. The PSU runs quietly under moderate loads thanks to its hybrid fan mode, and manages thermal performance well at higher loads. Though its single 12V-2×6 connector may be a drawback for some, its performance, reliability, and sleek design make it a great choice for demanding users.
MORE: Enermax PlatiGemini 1200W Review
1250-1500 Watts
The NZXT C1500 Platinum is a powerhouse designed for serious PC enthusiasts building ultra-high-performance systems. With 1500W of capacity and dual 12VHPWR connectors, it is ideal for setups running multiple GPUs. This PSU hits the sweet spot for efficiency, with 80Plus Platinum certification, delivering an impressive 92.6% efficiency at 115V and up to 93.7% at 230V. Its "Zero-Fan" mode keeps the fan completely off at up to 50% load, making it virtually silent under typical gaming conditions. When tested under heavy load, the C1500 remains reliable, handling heat with ease, making it perfect for gamers pushing their systems to the max. Priced at $370, this PSU is a viable top-tier option for enthusiasts running high-end gaming rigs with dual GPUs, offering great performance without an unreasonably high price tag.
Read: NZXT C1500 Platinum Review
>1600 Watts
The power supply range above 1500 Watts presents a unique challenge, particularly in the U.S., where grid voltage and regulatory limitations restrict availability. In this tier, prices tend to soar, indicating that these units are crafted for those seeking uncompromising performance, with cost being of no concern. The Seasonic Prime TX-1600 exemplifies this approach, engineered to provide incomparable electrical and acoustic performance for high-demand PCs that consistently draw over 1 kW of power. Constructed with premium components, it delivers a steady 1600 Watts effortlessly even under harsh conditions. However, its $600 price tag is not just high but nonsensically steep, even for those seeking the absolute best in PC hardware.
MORE: Seasonic Prime TX-1600 Review
SFX PSU <800 Watts
The Corsair SF750 Platinum (2024) is a high-performance SFX power supply, designed for compact builds that demand high performance. It is based on a refined version of the Great Wall platform that its predecessor used, now updated to meet the ATX 3.1 standard. It delivers cutting-edge power efficiency and reliability in its class. Corsair uses premium components, including all-Japanese capacitors, ensuring durability and performance. Certified by both Cybenetics and CLEAResult with Platinum efficiency, the SF750 delivers outstanding electrical performance. Despite its small form factor, it also maintains an excellent thermal-to-acoustic balance, running quietly under typical loads. At $170, it is a steep investment, but a necessary one for gamers seeking a high-performance, ATX 3.1-compliant SFX PSU. Perfect for compact gaming builds.
MORE: Corsair SF750 Platinum (2024) Review
SFX PSU >800 Watts
The SilverStone Technology Extreme 1200R Platinum SFX-L PSU is a powerhouse tailored for PC enthusiasts seeking top-tier performance in a compact form factor. Built on the robust Enhance platform, it adheres to the ATX 3.1 and SFX12V 4.1 standards, ensuring compatibility and reliability. This unit boasts high-quality components that enable it to deliver its full 1200W capacity continuously at an impressive ambient temperature of 50°C. With Cybenetics and CLEAResult certifications both affirming its Platinum efficiency, the Extreme 1200R excels in electrical performance. Moreover, its thermal-to-acoustics balance is commendable for a unit of such compact dimensions, making it a solid choice for those prioritizing silence without compromising power. While the $330 price tag is steep, it represents the investment required for those determined to secure the best SFX-L power supply on the market.
MORE: SilverStone Technology Extreme 1200R Platinum Review
Quick Power Supply Shopping Tips
Quick Power Supply Shopping Tips
Key Factor: Correct sizing. First and foremost, it is crucial to understand a system's power consumption, especially if future upgrades are planned. Modern PSUs operate most efficiently at around half their rated capacity, and contrary to popular belief, purchasing a higher-wattage PSU does not guarantee better performance. Efficiency drops significantly at low loads, particularly below 15%, with only the 80Plus Titanium certification requiring 90% efficiency at 10% load. While Cybenetics provides light-load efficiency data, this is not factored into its certification, which averages efficiency between 10% and 100% load. Therefore, an oversized PSU may result in poorer performance than a properly sized unit, often at a lower cost.
Avoiding Overestimation. The most common mistake in PSU selection is overestimating power needs. Builders often recommend 1000 W PSUs for systems with mid-to-high-end GPUs, though most systems with a mainstream CPU and a single GPU rarely exceed 550W. For example, a modern mid-range system with an AMD Ryzen processor and an AMD RX 7600 or NVIDIA RTX 4060 typically consumes no more than 350W under load. Even a high-end setup with an Intel Core i9-14900K and NVIDIA RTX 4090 usually peaks at 800W, yet many users still choose oversized PSUs.
Several reputable manufacturers and e-tailers offer PSU calculators to help estimate power needs, including:
- Cooler Master Power Calculator
- Seasonic Wattage Calculator
- MSI PSU Calculator
- be quiet! PSU Calculator
- Newegg PSU Calculator
While PSU calculators are useful, they rely on thermal design power (TDP), which often overestimates real-world power needs. Considering that the unit should operate at roughly half capacity, choosing a PSU based on these recommendations is not wrong; however, many users mistakenly opt for much higher wattages, leading to oversized, expensive units that cannot perform optimally.
ATX v3.0 / ATX v3.1 Compliance. The ATX v3.1 specification, introduced on September 13, 2023, quickly followed ATX v3.0 (released in February 2022) to address issues with the 12VHPWR connector and alleviate some testing procedures. The key update is the transition from the 12VHPWR connector to the 12V-2×6 connector, which features shorter sense pins that reduce the risk of overheating by ensuring proper cable connection before power delivery. However, this change only affects the connector on the device’s side. PSU manufacturers face minimal changes with ATX v3.1, as the physical cable remains the same, and many have simply rebranded their ATX v3.0 units. Full compliance requires integrating the 12V-2×6 connector on the PSU side, though the risk of overheating there is low. The rest of the ATX v3.1 updates primarily affect motherboard manufacturers or is meant to improve testing accessibility. From a PSU’s manufacturer point of view, the ATX v3.1 standard imposes less stringent requirements than its predecessor, meaning that PSUs certified under ATX v3.0 specifications are, by default, of a higher standard. When selecting a PSU, users should not discard ATX v3.0 designs as outdated or older. Users also need to be aware that ATX v3.0/v3.1 compliance does not necessitate the presence of a 12+4 PCI Express connector and there are several products in the market that do not have it at all.
Physical Considerations. Ensure that the PSU's physical dimensions are compatible with your case. Standard ATX cases will typically accommodate ATX-compliant PSUs, but some units may exceed the typical length of 5.5 inches. If you have a compact case, such as one that supports SFX power supplies, ensure that your chosen PSU fits accordingly.
For more on this subject, see our A Basic Guide To Motherboard, Case, and Power Supply Form Factors feature.
How we test Power Supplies
How we test Power Supplies
Effective power supply testing demands specialized equipment and precise methodology. It's not enough to connect a PSU to a PC and measure voltage with a basic multimeter. Professional testing requires programmable electronic loads, high-spec oscilloscopes, and detailed technical knowledge. Moreover, knowledge of the correct loading and testing protocols is essential, as these processes are governed by well-documented procedures detailed in technical papers and guides.
Programmable DC loads are essential for accurate testing. We use two Maynuo M9714 and two M9711 loads, capable of drawing 2400 Watts from 12 V line and 150 Watts from 3.3 V and 5 V lines respectively.
When assessing power supply performance, even the best multimeters are inadequate. An oscilloscope is indispensable, but not just any oscilloscope. The Intel ATX design guide specifies a minimum bandwidth of 20 MHz but, practically, digital oscilloscopes must be able to sample data at a rate at least ten times higher than the frequency being measured, meaning a 20 MHz oscilloscope should have a sampling rate of at least 200 MSa/s. Low-end oscilloscopes, particularly those that are USB-connected, simply cannot meet this requirement. In our testing setup, we employ a Rigol DS5042M oscilloscope with a bandwidth of 40 MHz and a real-time sampling rate of 500 MSa/s. While these specifications may seem impressive, even this instrument has limitations, such as automatically resolving the noise out of the ripple of a signal.
Efficiency testing, while simpler, still requires precision. Our programmable loads provide real-time power draw data, and we use an Extech 380803 power analyzer to measure true RMS values from the AC outlet. Testing is conducted at both 230V/50Hz and 115V/50Hz, with input voltage managed by a 3000VA Variac. It is crucial to use an analyzer capable of displaying true RMS values, as power supplies generate significant harmonic distortion.
Thermal and noise testing are more complex. Thermal testing is relatively simple, requiring only two high-precision UNI-T UT-325 digital thermometers with four probes to monitor ambient, exhaust, and heatsink temperatures. Noise testing, however, cannot be conducted during PSU operation due to the interference from testing equipment. Instead, we isolate the fan’s noise using a laser tachometer and test it separately with an adjustable DC power supply. Noise levels are recorded with an Extech HD600, in a quiet environment with a baseline noise of 30.4 dB(A).
We also developed a custom test fixture and hot box for more controlled testing. The hot box is a simple enclosure with an air-heating device that simulates real-world conditions by heating the air, not the box, allowing for testing at room temperature (25°C) and elevated temperatures (45°C). It is worth noting that efficiency certifications, such as 80Plus, are performed at room temperature, and a PSU may fail to meet its certification standards under elevated temperatures.
Efficiency certifications themselves follow different protocols. The CLEAResult 80Plus certification tests efficiency at specific load intervals (20%, 50%, and 100%), while the Cybenetics certification takes into account the average efficiency from 10% to 100% load. Our testing provides efficiency data from 5% to 100% load, as well as the average efficiency of a unit between 20% and 100% load. We chose to include 5% load testing as modern systems have their energy demands dropping dramatically while idling, which typically land at 5% to 10% capacity of a properly sized PSU. The conversion efficiency of switching power supplies drops significantly at very low loads, with drops exceeding 10% being common in many designs.
In conclusion, effective power supply testing requires precision instruments, a comprehensive understanding of testing methodologies, and carefully controlled conditions. Only by adhering to these standards can we obtain accurate data on PSU performance, efficiency, thermal behavior, and noise characteristics.
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