How to Choose a Power Supply

There are many considerations to take into account when purchasing your new PSU. A poor selection of PSU is not only dangerous for your computer, but dangerous for your own safety as well. A cheap power supply can easily destroy your computer and/or catch on fire. An exploding PSU that catches fire can be deadly – it releases toxic smoke and can catch your entire residence on fire. There are a few manufacturers which I can recommend that have quality units (with isolated exceptions). These are:

If you know what to look for, quality power supplies can be found from other manufacturers. The new EVGA SuperNOVA series, for example, uses the new Superflower Leadex platform for the OEM which is extremely high quality. If you do not understand anything about power supplies, ask someone knowledgeable. Another thing to note, do not buy into the marketing. For example, Corsair has several good series, although that does not mean all of them are good quality. The CX, CS, and VS series are all lesser quality and should never be used in a high-end machine, although they are okay for office machines. Most people are not even aware that Corsair, and indeed most manufacturers, do not build their own power supplies. Their lower end models are generally from the likes of Channel Well Technology (CWT) while higher end models are Seasonic. Their flagship, the AX1500i, is a Flextronics based model of whom typically only make PSUs for servers which must be run in harsh conditions 24/7.

Don’t look at the brand on the label, look at the OEM. This means that I will often recommend a unit that is not from my list above. The Lepa G1600-MA is a rock solid PSU and it is an Enermax unit. The NZXT Hale90 850 is a Superflower unit. Superflower is a very good OEM, and any of their platforms after 2012 are very competitive with Seasonic, Etasis, Delta, etc. FSP is another OEM with good platforms as long as you get one of their high-end platforms like the Aurum series. So what makes one OEM better than another? Many things are considered, but nothing makes one OEM inherently better than another. CWT, for example, is a decent OEM if they are given the money to make a good platform. In the case of the Corsair CX series, for example, Corsair just wanted a cheap platform that they could relabel and sell. This build quality begins to show when you look at the insides of it. The primary capacitor for this platform is Capxon and the secondaries are Samxon. These are not first-tier capacitors and are not intended to be abused like they would be by a high-end machine. Yet, for the EVGA SuperNOVA G2/P2 series, EVGA worked with Superflower to build a strong platform. This quality again shows when you look inside – it is a very strong platform capable of running a high-end system.

How does efficiency factor into all of this?

A lot of people will look at the efficiency on the PSU’s sticker to decide which power supply to buy. This is bad practice and should not be done except when already comparing quality units! The ABS Majesty MJ1100-M is a gold rated power supply but it is a very poor unit. It is way out of spec when at load and is vastly overrated on wattage. 80+ certification is achieved by sending a single test unit to the 80+ lab. This means that a company can hand pick their best performing unit to skew results. The lab is also much cooler than your average PC case will get which tends to skew results as well. For a more comprehensive explanation, visit the link at the top for [H]OCP. Finally, efficiency only really matters when comparing quality units. The EVGA SuperNOVA G2 1000W is less efficient than the EVGA SuperNOVA T2 1000W. One is rated for Gold certification and the other is rated for Titanium certification. Both are highly regarded units however, with the only differences being the miniscule operating cost differences and slightly different heat output of these units.

Does the weight of the unit have anything to do with quality?

I was just recently asked this question but like the efficiency question it doesn’t have a definitive yes or no answer. A junk unit may be heavier than a non-junk unit. For weighting to really matter, you really need to be comparing two units that are very similar. In general, heavier units may be better than lighter units, but there are plenty of exceptions to the rule. I’d much rather be running a 350W Seasonic than a 1050W CoolMax PSU for example.

Why should I spend so much money on a PSU?

Power supplies are often overlooked and an afterthought when builders are choosing which components to use in their latest build. Power supplies are the most important component in your entire build. If you use a cheap power supply from the back of a white van, expect your other components to suffer for it. Cheap units often have out of spec voltage, out of spec ripple, and poor PFC if it exists at all. These cheap units will use the cheapest electronics one can find, often using questionable capacitors and bad soldering. If these units even have a warranty, they will likely be for one year, and the company may not even exist when the unit does die. On the other hand, a quality unit can last you a very long time. The EVGA SuperNOVA G2/P2/T2 series all have a 10 year warranty! Not only can you continue using this PSU for every build for the next 10 years, the quality control is much more substantial. The voltage is right on point, the ripple is almost non-existent, and the PFC is top-quality.

What happens if a power supply dies?

In general, a power supply will quietly take its last breath before never turning on again. This is true of most OEM units that come with your pre-built computer and for most enthusiast units. Occasionally, especially on junk units, a power supply can take other components with it. That $400 graphics card or $300 processor is no longer usable because you only wanted to spend $30 on a PSU instead of $80. In the worst case scenario, a power supply can catch on fire and burn up your PC and maybe even the rest of your residence. This is why it is very, very important that you do not skimp out on a power supply. Do not attempt to repair your PSU, throw it away! The only people who should attempt a repair on a power supply are those who work with electrical components as a career.

How much wattage do I actually need?

Probably not as much as you think. Most modern processors and graphics cards will get by on 450W just fine. A top of the line system that is heavily overclocked with one GPU will usually be fine on 850W, perhaps 1000W if you are overvolting. The only reason you should get a PSU over 1kW is if you are planning to run a machine in SLI or Crossfire. For a simple and easy to use calculator I recommend the eXtreme calculator hosted at outervision.

Thanks TH.