Computer Power Supplies

How To Choose A Power Supply

 

There are several things that you should consider when selecting a new power supply. While this is not an exhaustive list, below are some things to look out for.

 

Wattage

 

This is one of the most talked about specifications for a power supply, and for good reason. An undersized PSU can keep your system from functioning properly, cause random failures, and generally make for a bad day computing. 

 

But you don’t want to go far beyond the level of wattage that you need. It would be a waste of money, but it would also likely be inefficient at the power level you actually need. There’s no advantage to having a 1000 watt power supply in a system that draws 400 watts. 

 

There are many power supply calculators out there if you do a quick search, but here’s a quick estimate of what you’d need. If you are in doubt, go up one level or buy at the higher end of the recommended range, but don’t buy double what you need.

 

• 400-500W   

Great for basic PC builds, home office computers, and systems using built-in graphics. This could also work for a lower-end gaming system, but you’ll want more watts if you plan to overclock or go with a better graphics card.

• 500-750W  

This is the range you’ll want to aim for if you’re building a more serious gaming system. It’s also the right range for a system that has a high-end video card to use for 3D rendering. If you plan to overclock your CPU, you probably want one of these. 

• 750-1000W   

This is what you’ll want if you plan to build a high-end PC with multiple processors or with multiple high-end graphics cards.

• Over 1000W   

If you plan to build a super high-end computer, you may need a power supply in this range. This would be several high power GPUs, multiple CPUs, and several drives. Most people do not need this kind of power.

 

Quality

 

Quality is important. So how do you check the quality of the power supply before you buy it? Try checking the reputation and reviews online. If you look up the brand and see that many people receive units that die in a month, avoid that brand. There are so many power supply makers that it can be hard to know the quality of them all, but if you stick to the well-known brands you’ll likely be better off. 

 

Some of the better brands are:

 

• Corsair
• EVGA
• Thermaltake
• Silverstone
• Antec
• Seasonic
• be quiet!
• Cooler Master

 

If you stick to one of those or to another well-known brand and you read the reviews for the specific power supply, you should have a good idea of the quality.

 

Form Factor

 

Most of the time this isn’t going to be a problem, as a lot of systems will use the standard ATX power supply. But if you’re building a small form factor system, you’ll want a small form factor power supply. 

 

Also consider the dimensions of a power supply. Some power supplies are longer than others, and if you have a case where everything is very snug already, then adding a shorter power supply may be helpful.

 

Efficiency

 

Most power supplies are rated on efficiency using something called the 80 PLUS system. With this rating system, they calculate the efficiency of the power supply across different loads, 20%, 50%, and 100% load. A simplified explanation of the various levels are:

 

• 80 PLUS            At least 80% 
• 80 PLUS Bronze         At least 82%
• 80 PLUS Silver        At least 85%
• 80 PLUS Gold            At least 87%
• 80 PLUS Platinum        At least 89%
• 80 PLUS Titanium         At least 90%

 

Consider you have a 600 watt power supply that is 80% efficient. That means it’ll pull 750 watts from the mains power to provide you with that 600 watts. The extra 150 watts can turn into a lot of extra heat in the power supply, which can lead to a lower lifespan for your power supply. 

 

The same 600 watt power supply may only draw 675 watts if it was rated at 80 PLUS Platinum. That’s both a reduction in heat-related wear on your power supply, but it also can save money on your electric bill over time. 

 

Modularity

 

The modularity of a power supply is really just talking about whether the cables come permanently attached or whether you can leave part of the cables off if you do not use them. Leaving excess cables off can help airflow in your case, improving cooling. It can help the aesthetics, which can be important on an open-case system. And modular PSUs often make it easier to route cables around the case and through cable management, which can help clean it up even further.

 

Price

 

Most people have a limit on how much they can or want to spend when replacing a power supply, building a new system, or upgrading an old system. Price matters. However, you should always keep in mind that other things may matter more. No matter how cheap a power supply is, if it won’t fit in your case it doesn’t do you any good. You should never buy a PSU that provides lower wattage than you need just because it is cheaper.

 

What you can do is comparison shop. Look around at different websites and stores that sell computer parts to see who has the best price. Also compare different brands in the same range. If you need a 550W power supply and are thinking of getting a Corsair, also consider brands like EVGA or Thermaltake. And don’t just compare to other 550W supplies, check the 600W or 650W options. 

 

Consider the features you need. Maybe for your system you don’t really need full modularity. If that’s the case, the non-modular supply may be a little cheaper. Perhaps you don’t require as many PCIe connections. By comparing various power supplies, you could save some money.

 

Where To Buy A Power Supply

 

You can buy power supplies from most places that sell PC parts. This can be a local electronics retailer, but it can also include the big retail chains, such as:

 

• Amazon
• Newegg
• Micro Center
• Best Buy
• Walmart
• Target

 

You may be able to find the power supply you want in the store, but you’ll likely need to order from their site to get what you want. You can also buy directly from some of the manufacturers, such as Corsair, Thermaltake, EVGA, etc.

 

Alternatives

 

The only alternative to a new power supply is to make your current one work. Consider why you’re replacing it. If it has gone bad then you need to replace it. If you’re replacing it for another reason, there may be options.

 

If you are replacing your power supply because you’re installing new hardware, such as a video card, then you may be able to stick with the one you have. First of all, is there anything in your system you can do without? Remove any unnecessary drives or switch to a lower-end sound card, then recalculate how much power you need. Maybe your current power supply will work.

 

One option you may have if you are upgrading the PSU only because of a new graphics card is to instead switch to a processor that has an integrated GPU. This only works if your system accommodates an integrated GPU. If it does, you may save enough energy to continue using your current power supply.

 

Frequently Asked Questions

 

How Do I Know If My Power Supply Is Failing?

 

It’s hard to know if you have a power supply that is in the process of failing until it completely fails. Sometimes, though, a power supply does give signals that it is on its way out. 

 

One symptom of a failing power supply can be the sudden occurrence of the blue screen of death in Windows. This usually comes up with a message talking about a fatal error. 

 

You may see random shutdowns on your system, the computer may freeze, or the computer may not start at all. You may have to press the power button two or three times before the computer starts properly. While some of these are often caused by other issues, these are all signs that your power supply may be going bad. 

 

Does Power Supply Efficiency Matter?

 

Efficiency can matter a lot when selecting a power supply. If you are a heavy user, an inefficient power supply could use $50-60 or more electricity per year over what an efficient power supply unit would use. Consider the possibility that you could have a power supply for at least five years. That adds up to $250 or more that you spent extra on your utility bills. That makes that cheap power supply really expensive in the long run.

 

Stick with power supplies that are 80 PLUS rated. When selecting between 80 PLUS ratings, there isn’t a lot of difference between Silver and Gold when it comes to how much electricity they use, but it still adds up on your electric bill. Take that into account when you are comparing prices.