Does the power supply inside your the PC provide enough juice?

GPU Power

GPU (Image credit: Windows Central)

When looking at various build plans or a new component to upgrade, one has to consider the power supply unit. Can it provide enough power? Is it from a reliable brand to ensure a stable supply? These are but just two questions that will need to be answered and thankfully we can lend a helping hand, not to mention there are handy calculator tools available that can determine whether or not you require additional power.

The power supply unit needs to provide enough stable electricity to the motherboard, CPU, GPU, connected hard drives, any case mods and fans. While manufacturers offer up TDP calculations and the like, it remains fairly difficult to accurately calculate exactly how much power you're going to need.

There's a safe margin that's considered more than adequate for a single-GPU PC build: 500W. You'll be able to power not only the GPU, which requires separate power connections as you hit the more demanding segments, but also numerous fans, some lighting and everything else in-between. The goal is to not go with the highest watt, but the best in the business for your buck.

It's better to go for a reliable model from a reputable brand that has just 500W-750W capacity over a more affordable 1500W PSU. Often the marketed capacity is what the unit will be able to provide at peak under full load. Your PC not only requires power, but "clean" and stable power. It's all about frequencies, how much juice is provided through the 12v rails, whether you have modular cables to keep everything tidy and improve airflow, silent operation, and higher efficiency.

Calculate your needs

There are a number of calculation tools available that help give you an idea as to what capacity you should be looking at. While we'd not recommend you need anything more than 500W or 750W at the most, if you're looking to throw in a second GPU, or simply wish to future proof for upgrades, you may need some more capacity. Find below a list of tools that can be used to estimate how much power your system may draw:

While we urge folk to give these tools a try if you're not entirely sure what you'll need, they shouldn't be used as final verdicts. After calculating your PC build, see our best power supply round-up and work from there.

Best power supplies for your PC

Rich Edmonds
Senior Editor, PC Build

Rich Edmonds is Senior Editor of PC hardware at Windows Central, covering everything related to PC components and NAS. He's been involved in technology for more than a decade and knows a thing or two about the magic inside a PC chassis. You can follow him over on Twitter at @RichEdmonds.

  • Coolio... I wasn't sure what should I do about the PSU, this helps.
  • These PC build articles are scattered all across WC. Would be great if you could compile them so we can go step by step
  • 850 Antec here.... Awesome PSU, and would never buy anything else (my old one lasted for about 15 years with no issues)
  • More importantly, power supplies are much less efficient when providing power near the low end of their capacity. It's much more efficient (less electricity cost) for a power supply operating at like 50-80% capacity than one running at 10% capacity. This article is a bit lightweight and should have at least addressed the 80-Plus certification program ratings ( nor does it provide a general discussion on how to determine what load your current system is drawing. However, I do agree that for most people there is no reason to go above 500 W from a high quality manufacturer. 
  • yes, I agree with you. Normal user who wants to play games and has only 1 GPU needs ONLY a power supply with max. 450W 80+ gold certification. No need for more W because modern CPU/mobo/SSD doesnt need a lot of electricity
  • Even 450-500 W is pretty generous, IMHO. Unfortunately, it's very difficult to find high-quality power supplies in the 350-400 W range, most units are either for niche form factors (SFX or rackmount), or are such garbage you wouldn't want them anywhere near your PC.
  • This was my thought as well. The efficiency of the PSU makes a big difference. The more efficient the more power is actually delivered to your computer and the less wasted energy due to design and heat.
  • Another important point to consider is to ensure that your UPS or lightning protecting power strip (or both) that you have your PC plugged into can deliver more than what the PC power supply can. Many years back, I learned this lesson through many frustrating blue screens while playing intense games. Before you bother troubleshooting your RAM, motherboard, CPU, etc. (because that's what the error codes will point you at), make sure you're giving then enough power! In my particular case, I had a 750W power supply, but only a 900VA UPS feeding it... I switched to a 1250VA UPS and my blue screens every 15 minutes were gone for good!
  • Great point. Thank you.
  • Cheap power supplies are probably the number one cause of BSOD, lockups, and crashing. But it is also the FIRST thing people and budget PCs cheap out on. Unfortunately, it is always Windows that gets the blame for it.
  • That pic of the CX750 is what I use. It just works.
  • Is it just me or does the title sounds wrong?
  • It's just you.
  • "...inside your the PC..." Yes, the title is grammatically incorrect. However your question is as equally incorrect. So it's a wash.
  • I'm thinking about adding a graphics card to my PC built in 2011 wher I've been using the integrated graphics from my I5 Ivy Bridge CPU for the past 5 years. That's really the only upgrade I need for this old computer. According to all of these calculators except Newegg, they recommend 330W of power if I want to add the Nvidia 1050 card that I've looked at. Newegg, on the other hand, recommends about 500W. Newegg's calculator is much less detailed about the computer components included. Is that the issue or is there a bit of a conflict of interest considering that they are in the business of selling PSU's directly to the public? I think my existing PSU is sufficient either way, but I was just curious.
  • I haven't looked at the tools to say what with Newegg would make theirs higher. It might be generic info that averages higher than what you use. It might have bad info on parts' power consumption. It might be aiming at the high-end of what a part can use, rather than an average use case from the others.
  • I'm good on my Corsair HX750 still. However, a SATA power connector broke on it recently (plastic, not calling or power problems). Shouldn't affect anything because I had an extra connector available, and I could probably just get another cable (modular PSUs are the best). Remember AMD CPUs suck power like crazy, so if you want one of those in a new build (not sure why you would, since they're all about three years old now), you might need something a little stronger on the PSU side.
  • "It's all about frequencies" Frequencies of what? Computer power supplies output DC, not AC.
  • Could be referring to bios settings but I'll use this opportunity to call out the purity of the input to the psu. If you're using those flat sine wave ups Ala cheap battery backups up to 300$(tech to get the good stuff may have gone down in price lately dunno) you're giving spoiled milk to your baby. They like simulated or best pure sine wave frequencies to feed power into them. If my points are off slightly please offer corrections it's been a few years since I had to research this stuff for my last build.
  • I use the Corsair CX750 PSU in my rig, its a couple of years old but has done me nicely through several upgrades. I don't have an uber 1337 rig but it does nicely and it's good to know I have power to play with should I need a more beefy upgrade.
  • Cooler master v850 here, and its awesome
  • I have been using a Corsair 850W modular PSU for years and just move it to each new build I do. It has been quite capable and no matter what I add or overclock the loads are always well below max.
  • Same. I also have a 1200w that's a beast. Platinum rated. Multicard crossfire setup from about 4 years ago. Corsair psu's are my favorite.
  • I have a CM V1000, it was on a great sale when I got it. But my criteria was nothing less than gold rated and I needed to make sure I had enough amps on 12v rail and for some future additions. I love this unit, completely silent an no vibrations and fully modular. Three years in now and no hiccups whatsoever.
  • has a built in one that let's you pick vetted components collects all your parts, and checks for compatibility, best price, and power consumption. You can see buildguides, reviews, and ask questions. It's a great place to organize your build and is quite helpful for finding everything you need. A good place to start is r/BuildaPC on reddit. LinusTechTips and JayzTwoCents are great YouTube resources for buildguides and first time PC builders, including soft and hardline water cooling.