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We’ve got an in-depth guide for all the power supply details, but the quick answer is that a power supply, or PSU, converts the energy from the outlet into a form that your computer can use. Basically, it’s what all the components need to function.
It is very common to need a new power supply with a new build. If this is your first build or a from-scratch build, then a PSU is an absolute necessity. If you’re building from an old PC and thinking about reusing your PSU, you might want to reconsider. If you have had a power surge or any electrical issues at all, I always recommend picking up a new power supply. Even if you haven’t had electrical issues, using a fresh power supply can help protect your components from failure.
Old power supplies can cause issues with newer components. A power supply will lose maximum wattage and efficiency as the years pass. They have a lot of electricity going through them and they do wear out. Looking at the warranty on a power supply is a good rule of thumb for a power supply’s expected life span. The manufacturer tests their products for durability with moderate regular use to determine how long they expect it to last. An older, used power supply will not have the same performance as a new one and its performance will drop every year.
Surges, blackouts, and brownouts are the bane of any electronic component, especially power supplies since they are the first components that an electrical current will go through and do their best to protect other computer parts. Surges in electricity will wreak havoc on electrical components, and the PSU is no exception.
A blackout is when there is an interruption in the electricity. It will cause your breaker switch to flip. That is a safety feature of a house in and of itself, but the electrical current can still cause problems and damage equipment. In this case, the power supply in a computer can be blown out and cease to function.
A brownout is similar, but it isn’t enough to cause the breaker to flip off, but you can see its effects with lights dimming in the house. These are also very dangerous because they cause damage over time and shorten the lifespan of your devices, such as power supplies.
Yes, there are protections that you can buy, such as surge protectors or even better battery backups with AVR protection, but they can’t protect against everything all the time. I always use battery backups with AVR and surge protection on my computer, but I always keep in mind that those devices also wear out and can’t protect against higher voltage surges than what they are rated for.
I have seen many computer builders who attempted to use faulty power supplies and paid for it in the end. A power supply hit by a surge or too many brownouts can lead to damage for your other components. A power supply can surge other components when they die, causing those parts to malfunction or even fail. I always recommend buying a new power supply when you’ve had electrical issues and a fresh PSU for a new build is never a bad idea.
It is very easy to calculate the wattage your computer is going to be using with a wattage calculator online, like the one on the Micro Center PC Builder. A power supply should be around twice the average amount of wattage your computer uses. This is because the power may spike to high wattages when under a heavy load. When power supplies are under a heavy load, they will be using more power. While you can use a power supply that is around what your PC “needs”, I don’t recommend it in most cases. When you have a power supply stressed to maximum wattage for long periods of time, it massively shortens the lifespan of the power supply.
If you think you will want to upgrade to a better graphics card and/or a higher wattage CPU in the lifespan of your power supply, I would recommend going above and beyond to get a higher wattage PSU that can support the future parts. While it costs a little extra now, it will save you from having to buy a new power supply in the future with that upgraded graphics card or processor! While that might not seem like a big deal now, when you have to rewire your whole case for a new PSU, you’ll regret it.
It is very important to check what size power supply your case will need. Most cases use a standard ATX power supply. Smaller cases, such as mini-ITX builds can use SFX power supplies instead. Check your case specs to make sure you’re getting the right power supply size!
Power efficiency is how much energy is expended in order to achieve the desired result. So, the higher the percentage of efficiency, the less energy it expends to do the task. This is important, because that extra wasted energy is more heat that will be released into your case. More heat means your parts will die faster and they will be closer to thermal throttling! Both things you want to avoid as much as possible on your computer. Less wasted energy also means less electricity used and that means you will spend less on your power bill as well.
The 80 PLUS Certification is one of the most important aspects when considering your power supply. Better ratings mean better power efficiency leading to a cooler, potentially faster computer, that costs less electricity to run. Check our guide for a full explainer!
Yes, you can go too high in wattage! Power supplies have a bell curve of efficiency in which your energy will be most effective. Keep that in mind for both your current build and what you think you may need down the road.
Your 24-pin to the motherboard power cable is an absolute must, and you may need a number of 4+4 pin cables for your motherboard power, depending on your motherboard. SATA power is needed for most Solid State and Hard Disk Drives. Some add-on boards will use these as well. Most modern high-end Graphics Cards will require 1-to-3 6+2 pin cables directly to them. It is important to note that the 8 pin connectors are separated into 4+4 and 6+2 so that you don’t use the wrong one for the wrong job!
Most decent power supplies come with all the cables they will realistically need. Just because you can buy a splitter for your 8 pin PCI-e cable for your new high-end GPU doesn’t mean you should! You still need a power supply that has the correct wattage to support that graphics card without damaging it.
You can absolutely damage or destroy components that are not connected to power correctly. If you’re using the wrong cable, you might not have the correct wattage to run that part, leading to undervolting. Most modern power supplies can protect the GPU so it won’t get damaged from undervoltage, but I personally don’t recommend taking the risk! And if your cables are damaged, sparks could fly and, when a fire breaks out, a damaged computer is the least of your worries.
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You should turn off and/or unplug your power supply when you are working on your computer. Accidentally turning it on when you don’t have it all put together could cause it to overheat or break. It’s also important to understand that turning it off isn’t the same as unplugging it. There is still electricity in the capacitors, keeping it from being shut off completely.
Most good power supplies have some kind of overvoltage protection. As it sounds, it helps the power supply not get overvolted. This goes a long way to help it from taking other parts with it when it dies. Just keep in mind, it helps, but it can still happen!
Some power supplies come with a PCI-E 8-pin power that has two 8 pins on one cable. It is a good rule of thumb to avoid using this method when possible. It can cause the rail on the power supply to be overloaded with electricity or for it not be enough power to run the component. This is more of a generalization as different power supplies supply different cables. It's not a must, but a recommendation to be safe as opposed to sorry!
When faced with the task of choosing an external power supply (EPS), it's important to consider several factors to ensure your application runs smoothly and efficiently. These include your system's power requirements, package type, dc plug, efficiency and safety standards, EMI and EMC regulatory standards and customization options.
In this article, we will discuss the key considerations for selecting an external power supply and provide some tips on how to choose the right EPS for the specific needs of your design.
The first consideration when selecting a power supply is determining your system’s power requirements. Understanding the wattage, voltage, and amperage your system load requires is essential for the operation and safety of your end system. This includes asking questions like, "does my system operate at a constant power level and what are the minimum and peak power requirements?" If you are unsure or have questions, CUI Inc's in-house engineering expertise can help.
2. Package Type - Desktop or Wall Plug?
External power supplies are generally offered in two package types: desktop or wall plug (fixed or multi-blade). For many applications either option will work. However, there are some reasons why you may select one over the other:
For an external adapter to power your design it needs a method of plugging into your system. If the receptacle or jack has already been selected, this will determine which dc plug you choose. One of the most common options is a 5.5 mm x 2.1 mm or "P5" dc barrel plug (5.5 mm OD, 2.1 mm ID, 9.5 mm L). CUI’s standard plug options include barrel plugs, USB, EIAJ, DIN, stripped and tinned, as well as locking and right angle options. If these don't meet your needs, we can work with you to implement your own plug onto the adapter.
In addition to the dc plug, you'll want to ensure the dc cord meets your needs. Is it long enough to reach your product? Does it have the desired appearance and pliability? It is important to understand that modifying the dc cord can impact both efficiency and safety regulations.
Making sure you've considered the end market where your system will be implemented is critical. Many countries have efficiency standards which regulate the amount of energy that may be "wasted" by external power supplies. Whether it's Level VI (US), CoC Tier 2 (EU), or ErP Lot 7 (EU) efficiency standards, CUI offers compliant models and can help you navigate the complex and dynamic regulatory landscape.
In addition to efficiency standards, it is imperative to make sure your adapter has the proper safety standards for the end application. For example, medical products need the -1 certification and products for ICT/AV applications need the -1 certification.
Many countries require agency marks which are unique to that country. Specialized design and testing are sometimes required to obtain these country-specific certifications. CUI has the experience and knowledge to work with you to meet your country-specific agency mark needs.
5. EMI and EMC
Many electronic products offered for sale are required to meet EMI and EMC (Electromagnetic Interference and Electromagnetic Compatibility) regulatory requirements. These requirements ensure that your product will not interfere with the proper operation of other products and similarly that the proper operation of your product will not be affected by other products. Although CUI external power supplies are certified to meet EMI and EMC regulatory standards, it is probable that your system (including the power supply) will also need to be tested and certified.
Another important consideration and question to ask is, "how well will the adapter aesthetically integrate with my system?" If your design has a desired look-and-feel and you care about the customer experience of your product, then don't let the adapter be an afterthought. If your product has been intentionally designed with a specific color, then a black adapter may not integrate well. Consider color, texture, packaging, and even adding your logo to the power supply. CUI specializes in a range of customizable branding options.
Selecting a power supply for your new product is not a difficult task, but there may be subtle issues that affect the selection process. By working with an experienced power supply company, such as CUI, you can ensure that your power supply not only properly supports the operation of your product but also enhances the value of your product for your customer. CUI has a broad portfolio of standard designs we can customize to meet your specific application needs.
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