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The PC power supply unit (PSU) is often an overlooked component in computers. You might not find the PSU brand name and specifications on product pages for pre-built PCs. If you’re upgrading or building a PC from scratch, finding the best power supply for a computer is critical for stability of the system. Understand a few PSU basics and answering the question of what power supply do I need is fairly easy.

What is a PSU? It’s a wattage delivery system

Each component in the PC draws a certain wattage—everything from the video card to the case fans has a wattage requirement. A PC power supply draws power from the wall socket and delivers it to each component. Each PSU has a wattage rating (500W, 750W, 1000W) that denotes how much power it is capable of delivering.

The PC power supply needs to have adequate headroom for the sum total of the components’ wattage requirement; if the output is short of what the PC demands, the system will power off intermittently or not power on at all.

Use a wattage calculator to find PC power needs

How many watts does my computer need? A PC wattage calculator generates an estimate for the major power-drawing components. Use the Newegg PC wattage calculator; add another 10-20% to the wattage total for a buffer.

What PSU brand is the best?

Brand is a fundamental piece of your buying decision. Credibility does not establish itself overnight; it is the source of promise, quality, and trust that creates customer loyalty. Can I tell you the best pc power supply brand out there? That’s probably impossible in a purely objective sense, but I have data to show the top three best-selling power supply brands by class at Newegg. Always check customer reviews before purchasing.

PSU brand

PC power supply form factors

PSUs are purposely built to fit into specific computer case sizes. Some have extra connectors for server motherboards (EPS12Vs). PSU form factor name aligns with the case size form factor name. Full and mid-towers fit ATX, ATX12V, and ATX12V /EPS12V PSUs. Micro ATX / Mini ITX power supply types fit in the respective case sizes.

What does 80 PLUS mean?

The hardware consultancy Ecos Plug Load Solutions (EPLS) launched the 80 PLUS standard for PSUs in 2005. A PSU with 80 PLUS-branded certification delivers 80% energy efficiency while running at various load capacities. On average, users are able to save 40.5W of AC power even at 250W output. Efficient power use generates less heat and noise as well.

80 PLUS Levels

PCs and power supplies undergo rigorous safety testing by public and private agencies. A faulty PSU is a fire hazard so it has extra layers of compliance to meet. The following regulatory compliances are commonly declared by the power supply manufacturers: TUV, UL, CE, CB, RoHS, and FCC.

Power connectors & cabling

Most modern PSUS have 24 pin internal power connectors; some have what is called 20+4 pin connectors. What’s the difference? The 24 pin is just one connector; and the 20+4 is one 20 pin connector where at least 4 of the pins that detach to run power to specific types of motherboards and components. Power connectors in addition to the 20+4 pin are the 6+2 pin for components in the PCI-E slot of the motherboard (graphics cards, M2 SSDs), and 4 pin SATA connectors for data drives, among others. Modular power supplies ease  recommended for custom PC builds and upgrades.

modular PSU cables

Modular PSU power connectors

Modular PC power supplies have connectors that attach and detach from the face plate of the PSU. This means you can remove unneeded power connectors, or add extras when upgrading a PC. Modular PSUs ease cable management in custom PC builds.

Reliability is measured by MTBF—mean time between failures

Mean time between failures (MTBF) is a reliability measure based on lab testing and engineering analyses. A typical MTBF parameter might be 100,000 hour MTBF at 25 degrees Celsius.  It is the average time of failure for the component; some may fail after one hour, others may exceed 100,000—it is simply a calculation of the average.


The price of a PC power supply is mostly tied to its wattage output. Below are Newegg’s best-selling PSUs for the first half of 2016; this data is a good indicator of acceptable of price range by PSU class.

Item Brand Wattage  Price MTBF (hrs) Modular Main Connector
17-438-015 EVGA 80Plus 430W  $  29.99 NA No 24Pin
17-139-026 Corsair Bronze 430W  $  39.99 100K No 20+4Pin
17-438-012 EVGA Bronze 500W  $ 42.99 100K No 24Pin
17-139-027 Corsair Bronze 500W  $ 49.89 100K No 20+4Pin
17-438-053 EVGA Gold 550W  $  89.99 100K Full 24Pin
17-438-014 EVGA 600W  $  49.99 100K No 20+4Pin
17-139-028 Corsair Bronze 750W  $  69.99 100K No 24pin ATX
17-139-142 Corsair Gold 750W  $  99.99 100K Full 20+4Pin
17-438-017 EVGA Gold 750W  $ 119.99 100K Full 24Pin
17-438-018 EVGA Gold 850W  $ 139.99 100K Full 24Pin


In Summary

A high efficiency power supplies save energy and give off less heat that results in making much cooler PC environment and less noise. 80 PLUS and Safety compliance regulatory are also critical factors that mitigate potential risks of overheating, inefficiency power usage, or any other power supply failure. A reputable brand name, good customer reviews, and affordable pricing would work for me. What is your priority for pc power supply?

Adam Lovinus

Author Adam Lovinus

A tech writer and Raspberry Pi enthusiast from Orange County, California.

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