When you are building a PCthe Power Supply Unit (PSU) is not usually the component you daydream about. It is not as sexy as a top-tier GPU or as flashy as RGB parts. But think of the PSU as the heart of your system. Just as a weak heart limits the bodya subpar PSU limits (and endangers) your rig. Its job is deceptively simple: convert the volatile High-Voltage Alternating Current (AC) from your wall outlet into stable Direct Current (DC) for your components. Howeverdoing this reliably is what separates a long-lasting PC from a fire hazard.
Choosing the right unit involves a mix of hard math and personal preference.
Strictly speakingwattage mattersbut the Efficiency Curve is paramount. We recommend aiming for a unit that operates near 50% load for optimal thermal performance and longevity. It is also vital to look beyond basic efficiency ratings and examine our power quality measurementswhich reveal how stable and 'clean' the voltage output truly is. On the subjective sidedesign plays a major role. For a streamlined chassislook for fully modular units that eliminate cable clutter and improve airflow. Remember that units with similar price-to-performance ratios can feature vastly different industrial designsso pick one that matches your build’s theme.
A high-quality PSU does more than just push power; it acts as a firewall between the grid and your expensive hardware. If a PSU lacks a comprehensive protection suiteit is not just a bad purchase – it is a liability.
The Best Power Supplies You Can Buy Today
Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
Best Cheap PSU ($60 or less)
The MSI MAG A550BN is a solid power supply unit (PSU) built on a reliablethough datedCWT platform. It delivers dependable performance with decent quality componentsensuring stability and longevity for your system. Certified 80Plus Bronzethis PSU provides passable efficiency without breaking the bank. While it lacks modularitythe sleek design adds an aesthetic edge to your build. Most importantlyit includes all essential protections such as OVPOCPOPPand SCPsafeguarding your hardware. Priced at just $50it is a great choice for budget-conscious users building low-cost workstations or entry-level gaming setups.
MORE: MSI MAG A550BN PSU 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 stabilitysolid performanceand long-term durabilitythanks to its dependable HEC/Compucase design and 10-year warranty. It features stable voltage regulation and effective ripple controlmeeting its 80Plus Gold rating without exceeding it. The unit balances low noise levels during typical usebut under heavier loadsits acoustics worsenreflecting a trade-off between quiet operation and thermal management.
MORE: Be Quiet Straight Power 12 750W PSU Review
Up to 850 Watts
The Cooler Master MWE Gold 850 V3 is a reliablecompetitively priced 850 watts PSU that is ATX 3.1 / PCIe 5.1 compliant and comes with a 10-year manufacturer’s warranty. Its efficiency is thrice-certified (80Plus GoldPPLP.info Goldand Cybenetics Platinum)with the Cooler Master MWE Gold 850 V3 displaying outstanding low-to-mid range efficiency under typical operating conditions. It is built by LITEONone of the most experienced OEMsand is a great solution for users who want a great all-around performer at a reasonable price without breaking the bank.
Read: Cooler Master MWE Gold 850 V3 review
Up to 1000 Watts
The be quiet! Dark Power 13 1000W PSU is a premium offering built on an excellent FSP platformdelivering top-tier performance and efficiency. Both CLEAResult and Cybenetics certify it as Titaniumshowcasing its exceptional electrical efficiency. This PSU excels in power qualityensuring stable and clean output while maintaining impressively low noise levels under any load. Priced at $270it is a solid deal for a 1000W Titanium-certified unitbut with frequent discounts dropping it to $220it becomes unbeatable in its classmaking it a top choice for high-performance gaming or workstation builds.
MORE: be quiet! Dark Power 13 1300W Review
Up to 1200 Watts
The Montech Century II Gold 1050W PSU is a well-engineered power supply designed for mainstream gaming and enthusiast PCs. Priced at just $110it offers impressive value with quality components from manufacturers like Nippon Chemi-ConRubyconand Toshin Kogyoand comes with a comprehensive 10-year warranty. It meets ATX 3.1 standardsdelivering solid efficiency with 80Plus Gold certificationachieving 90.3% average efficiency at 115 VAC and 91.1% at 230 VAC. The PSU runs silently under moderate loads thanks to its hybrid fan modethough the triangle-centered fan grid may cause aerodynamic turbulence at higher speeds. While its single 12V-2x6 connector and shared PCIe cables may limit expansionits excellent power qualitythermal performanceand exceptional pricing make it an outstanding choice for budget-conscious builders seeking reliable power for high-performance systems.
MORE: Montech Century II Gold 1050W ATX 3.1 power supply 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 connectorsit is ideal for setups running multiple GPUs. This PSU hits the sweet spot for efficiencywith 80Plus Platinum certificationdelivering 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% loadmaking it virtually silent under typical gaming conditions. When tested under heavy loadthe C1500 remains reliablehandling heat with easemaking it perfect for gamers pushing their systems to the max. Priced at $370this PSU is a viable top-tier option for enthusiasts running high-end gaming rigs with dual GPUsoffering great performance without an unreasonably high price tag.
Read: NZXT C1500 Platinum Review
>1600 Watts
The Seasonic Prime TX-1600 Noctua Edition is a flagship 1600-watt power supply unit designed for extreme performance and reliability. A collaboration between Seasonic and Noctuathis power supply unit (PSU) combines cutting-edge power delivery with advanced cooling technology. It complies with ATX 3.1 and PCIe 5.1 standardsensuring compatibility with the latest high-demand systems and hardware. The Seasonic Prime TX-1600 Noctua Edition excels in efficiencymeeting the requirements for both 80Plus Titanium and Cybenetics Titanium certificationswhile offering overall performance that sets the industry benchmarks. Priced at $570it targets professional users and enthusiasts who prioritize top-tier performance and quality.
MORE: Seasonic Prime TX-1600 Noctua Edition Review
SFX PSU <800 Watts
The Corsair SF750 Platinum (2024) is a high-performance SFX power supplydesigned for compact builds that demand high performance. It is based on a refined version of the Great Wall platform that its predecessor usednow updated to meet the ATX 3.1 standard. It delivers cutting-edge power efficiency and reliability in its class. Corsair uses premium componentsincluding all-Japanese capacitorsensuring durability and performance. Certified by both Cybenetics and CLEAResult with Platinum efficiencythe SF750 delivers outstanding electrical performance. Despite its small form factorit also maintains an excellent thermal-to-acoustic balancerunning quietly under typical loads. At $170it is a steep investmentbut a necessary one for gamers seeking a high-performanceATX 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 platformit adheres to the ATX 3.1 and SFX12V 4.1 standardsensuring 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 efficiencythe Extreme 1200R excels in electrical performance. Moreoverits thermal-to-acoustics balance is commendable for a unit of such compact dimensionsmaking it a solid choice for those prioritizing silence without compromising power. While the $330 price tag is steepit 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 foremostit is crucial to understand a system's power consumptionespecially if future upgrades are planned. Modern PSUs operate most efficiently at around half their rated capacityand contrary to popular beliefpurchasing a higher-wattage PSU does not guarantee better performance. Efficiency drops significantly at low loadsparticularly below 15%with only the 80Plus Titanium certification requiring 90% efficiency at 10% load. While Cybenetics provides light-load efficiency datathis is not factored into its certificationwhich averages efficiency between 10% and 100% load. Thereforean oversized PSU may result in poorer performance than a properly sized unitoften 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 GPUsthough most systems with a mainstream CPU and a single GPU rarely exceed 550W. For examplea 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 800Wyet many users still choose oversized PSUs.
Several reputable manufacturers and e-tailers offer PSU calculators to help estimate power needsincluding:
- Cooler Master Power Calculator
- Seasonic Wattage Calculator
- MSI PSU Calculator
- be quiet! PSU Calculator
- Newegg PSU Calculator
While PSU calculators are usefulthey rely on thermal design power (TDP)which often overestimates real-world power needs. Considering that the unit should operate at roughly half capacitychoosing a PSU based on these recommendations is not wrong; howevermany users mistakenly opt for much higher wattagesleading to oversizedexpensive units that cannot perform optimally.
ATX v3.0 / ATX v3.1 Compliance. The ATX v3.1 specificationintroduced on September 132023quickly 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 connectorwhich features shorter sense pins that reduce the risk of overheating by ensuring proper cable connection before power delivery. Howeverthis change only affects the connector on the device’s side. PSU manufacturers face minimal changes with ATX v3.1as the physical cable remains the sameand many have simply rebranded their ATX v3.0 units. Full compliance requires integrating the 12V-2×6 connector on the PSU sidethough 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 viewthe ATX v3.1 standard imposes less stringent requirements than its predecessormeaning that PSUs certified under ATX v3.0 specifications areby defaultof a higher standard. When selecting a PSUusers 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 PSUsbut some units may exceed the typical length of 5.5 inches. If you have a compact casesuch as one that supports SFX power suppliesensure that your chosen PSU fits accordingly.
For more on this subjectsee our A Basic Guide To MotherboardCaseand 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 loadshigh-spec oscilloscopesand detailed technical knowledge. Moreoverknowledge of the correct loading and testing protocols is essentialas 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 loadscapable of drawing 2400 Watts from 12 V line and 150 Watts from 3.3 V and 5 V lines respectively.
When assessing power supply performanceeven the best multimeters are inadequate. An oscilloscope is indispensablebut not just any oscilloscope. The Intel ATX design guide specifies a minimum bandwidth of 20 MHz butpracticallydigital oscilloscopes must be able to sample data at a rate at least ten times higher than the frequency being measuredmeaning a 20 MHz oscilloscope should have a sampling rate of at least 200 MSa/s. Low-end oscilloscopesparticularly those that are USB-connectedsimply cannot meet this requirement. In our testing setupwe 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 impressiveeven this instrument has limitationssuch as automatically resolving the noise out of the ripple of a signal.
Efficiency testingwhile simplerstill requires precision. Our programmable loads provide real-time power draw dataand 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/50Hzwith input voltage managed by a 3000VA Variac. It is crucial to use an analyzer capable of displaying true RMS valuesas power supplies generate significant harmonic distortion.
Thermal and noise testing are more complex. Thermal testing is relatively simplerequiring only two high-precision UNI-T UT-325 digital thermometers with four probes to monitor ambientexhaustand heatsink temperatures. Noise testinghowevercannot be conducted during PSU operation due to the interference from testing equipment. Insteadwe 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 HD600in 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 airnot the boxallowing for testing at room temperature (25°C) and elevated temperatures (45°C). It is worth noting that efficiency certificationssuch as 80Plusare performed at room temperatureand 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% loadas 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 idlingwhich typically land at 5% to 10% capacity of a properly sized PSU. The conversion efficiency of switching power supplies drops significantly at very low loadswith drops exceeding 10% being common in many designs.
In conclusioneffective power supply testing requires precision instrumentsa comprehensive understanding of testing methodologiesand carefully controlled conditions. Only by adhering to these standards can we obtain accurate data on PSU performanceefficiencythermal behaviorand noise characteristics.
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