The PSU (Power Supply Unit) is one of the scariest parts of the build because you’re dealing with actual mains power (well, on one end – the other end is low voltage power!). You also have LOADS of PSU cables with different functions – ranging from Molex to SATA and PCIe to CPU and ATX 24-pins.
Also some of these cables have changed due to the new ATX 3.0 (and 3.1) specifications. So in this video I run through all the different PSU connectors, and I also explain what you need to do with each cable.
If you prefer text over video, please read on for the guide/transcript version of this video.
Video Transcript And Guide
ATX 3.0 (and 3.1) PSUs

Hey everyone, the power supply unit seemed like one of the scariest bits of a computer build because, after all, you put in mains power into your computer, and then all of a sudden, when you open the box, you’ve got all of these cables, and it’s really confusing to know what to actually do with it. Well, in this guide, I’m going to show you exactly how you plug in each cable into your power supply unit, and I’m also going to talk about the differences with the new ATX 3.0 and 3.1 power standards, which some people call PCI Express Gen 5 power supply units, but that’s not completely accurate.
The 24-Pin ATX Motherboard Cable

So, let’s get started with the motherboard slot. So, that is, as we probably know, this big monstrous cable. It’s always a thick, bulky cable. The first thing you probably notice is it has two ends which you have to plug into your power supply unit. You have to plug both of them in. Not all power supply units have this; some of them are just a 24-pin thing you plug into your power supply unit, but most of them have this split thing, and you have to plug both in. So, they go in, one would go into there, and the other one would just go into there. Fairly simple. And then, the other end, ideally, you can route it behind your motherboard tray and your case, and then you just pop out a tiny little end bit to actually plug into your motherboard. That’s going to look a lot neater than having all of this monstrous cable actually running through your case and ruining the aesthetics of it. So, if you can, try and route this through and just bend this as much as you can. It’s not going to break. Bend it as much as you can and plug that into your motherboard so you’ve got as little of this monstrous cable as possible on show. So, that covers the motherboard, and I probably can’t get this cable out now…
Molex – Still?

The next thing is SATA, or on some PSUs, they might see things like peripherals or Molex or SATA and things like that. So, we’ll start off with Molex. This is to power old-style fans. It’s very rare that you actually get these anymore because you can’t actually control the speed of your fans. They just run 100%, and it makes an absolute racket. But in terms of actually plugging them in, usually, what many PSUs actually do is you plug them into the same bit as the bit that says SATA and PATA, or peripherals. So, you just plug it in there, and you plug in your fans or any other Molex devices into that. Let’s ignore that for now because it’s unlikely you’re actually going to have that.
SATA/PATA/Peripherals

The next thing you’re actually going to have is your SATA cables. You might not need these at all if you’re going with an NVMe drive, but there are some cases where you’ll actually need your SATA power. So, I wanted to discuss that. So, again, you’ll plug this into the bit that says SATA or PATA. There’s not much difference between SATA and PATA; it’s slightly different power deliveries, basically. But many power supply units give you the exact same cable for both SATA and PATA, and they actually will say things like SATA and PATA, or SATA and peripherals. You plug this in, and then if you’ve got a SATA hard drive or a SATA SSD, you’ll plug that into there, and then obviously, you’ve actually got a data cable as well that you’ll need to plug into your hard drive and then connect into your motherboard to actually give the data from your hard drive or your SSD into the motherboard into the computer essentially. That’s the downside of things like SATA hard drives and SATA SSDs because you actually need two cables: one for your power and one for your data, and it gets a bit messy, which is where NVMe SSDs are brilliant because you just plug them in, and that’s the end of it.
SATA PSU Power For Case Fans

But that’s not the only reason you might need a SATA cable. If you’ve got a fan controller at the front of your case or maybe an extra USB hub or an optical drive if you’re really old school, you will need a SATA cable to actually power that. That’s usually how they’re powered. So, in that case, even if you’ve got an NVMe drive, you’re still going to need to plug this in and use this, which is a little bit annoying because it means more cables in your case. But if you need it, you need it.
The other reason you might need a SATA cable is if you’ve got more than three or four fans. You can’t power that off one motherboard header because that might be overloading it. So, if your motherboard has two or three fan headers, great, make sure you use them. But if you’ve got more than that, and you’re going to overload things, you’ll probably end up with a fan hub. So, what would happen is you’d actually plug all your fans into there, and then you need to give it extra SATA power. So, you’d actually end up plugging your cable into there. If I plug that in, and then you would plug this ultimately into your power supply unit. So, that would plug in there, all your fans would go into there, hopefully at the back of your case, so that you don’t have cables everywhere, and that’s how you do that. But that’s covering SATA and PATA, or peripherals, as my old power supply unit calls it.
CPU Cables

And then we come to the CPU and the PCI Express cables, and this is where it gets a bit scary because if you get your CPU cable and you plug it in, and then maybe you’re rushing and you accidentally get this cable and you plug it into your graphics card, bad things will happen. That’s because this end, at least it says CPU, that has to go with your motherboard, and that is only for powering your CPU. It’s not actually for powering your graphics cards. You might not physically be able to fit this into a graphics card, but in some cases with some cables and some power supply units or GPUs, it might actually be possible. So, just be aware of that. You should never have the CPU cable plugged into your power supply unit and then accidentally power your GPU with that. If you’re in any doubt, check out your PSU manual just to make sure you’re not, you know, going down the wrong path and accidentally nuking your graphics card or something. With Corsair, at least, it does say CPU on the actual cable, so hopefully, you won’t make that mistake
Why Two CPU Cables?

But it is worth mentioning that before we move on and talk about graphics cards, there is one other key point about your CPU cables. Your power supply unit might come with two of them. So, my Corsair one’s did, and like your motherboard cable actually has two ends, and you need to plug both of them into your PSU. With your CPU, you often only need to have one of the cables. So, you can get rid of one of them, and you just plug one of them into your power supply unit. You’ll either be marked as just CPU, or in Corsair’s case, they often just say PCI Express *slash* CPU. So, you can plug into any of the ports there, but then, as I said, make sure when it says CPU on the cable, this only goes into your motherboard in the top left-hand corner, usually to actually power your CPU. Don’t try and plug this into your graphics card.
The reason you have two cables, I should say, is that if you had some really, really powerful CPU, and maybe you’re overclocking it, it’s possible that this one cable won’t actually supply enough power to your CPU. As said, if it’s a really powerful one and you’ve overclocked it, this might not be enough, and that’s where the second cable will come in. But in general, you probably get by on just one. I mean, my main computer is a 12-core Ryzen CPU, the 5900X, it works just fine with one cable. I’ve never had any issues with it at all. But if you had something more powerful, maybe a Threadripper one you were looking at overclocking or crazy stuff with, you probably then need two CPU cables. So, that covers that.
PCIe Cables/Powering GPUs

And we now come to powering our graphics cards. There was a time where graphics cards were really simple and low-powered, and just plugging them into your motherboard would get 75 watts of power from the motherboard PCI Express slot, and that would be it, job done. You wouldn’t need to do anything else. There’s no PCI Express connectors.
But things have got a lot harder in recent years because graphics cards have got bigger and more powerful in recent years, and that’s where a PCI Express cable comes in. So, with that one, what we have to do is plug one end into our power supply unit and the other end into our graphics card. But there is a problem.
Warning About The Pigtail Connector

I talk about this more in another video. Well, I won’t talk about it too much in this one, but basically, if your graphics card needs more than 225 watts of power, you probably won’t be able to just get by with a single cable, even if it has this horrible pigtail connector thing, which I call “devil spawn.” It’s unlikely you can actually plug both of these ends into your graphics card if it needs two different connectors. That is because often these cables can’t actually deliver too much power. They can often deliver 150 to 200 watts, depending on the cable. So, if your graphics card is some super hungry 300-watt beast, then you can’t just get by on a single cable. What you’ve got to do in that case is run a separate one from your PSU. So, you would plug it in, and you would then run that to your graphics card, and you should actually rely on having two separate cables for that. As I said, I talk about this more in another video, so check that out.
12vhpwr and 12v-2×6 Cables

But that’s a general rule, other than if you have a modern Nvidia card. Modern Nvidia cards don’t support these 6 plus 2 or 8-pin PCI Express connectors. What they actually use is some new standard known as the 12V power connector. It’s this particular connector where it often comes with two ends from your power display unit, and then you’ve got this horrible 12-pin connector. The reason I say it’s horrible, it’s actually not too bad, but the reason I say it’s horrible is in the early days, but the actual connector was melting and caused no end of issues. It was all over the news. A lot of that has been sorted now, and many of the issues were with people who were actually using third-party connectors, which is never a good idea, especially with a new standard.
But basically, if you do have a modern Nvidia graphics card, what you actually need to do is make sure you plug both ends into your power supply unit. Don’t skimp on that. You must make sure you plug both ends into your power supply unit, and then when it comes to your graphics card, you plug this into your graphics card. Make sure you plug it in completely tight. There shouldn’t be any gap or anything else between the actual connector and the graphics card. The reason I say that is if there is any gap, it might actually cause, you know, the connector to burn out. That’s actually what was causing some of the burnouts in the earlier days of this new connector being introduced. So, if you do have a modern Nvidia card, make sure you plug both ends into your power supply unit, and then make sure you actually plug it all the way in. I know I’ve just said that, and I’m repeating myself, but please make sure you do that.
ATX 3.1 Changes (12v-2×6)
So, that is with ATX 3.0, and this connector is called the 12-volt power [12VHPWR] connector. However, that has changed a little bit for the ATX 3.1 standard, where they’ve made this connector a little bit safer, just due to all the melting issues and the bad news stories and stuff. It’s not much different. I think they’ve made the pins very slightly shorter, which allows you to make sure you plug things all the way in, and you don’t have any of the issues with you’ve got a partial contact, and then a burnout, which was a bit scary. But basically, that’s the main difference between ATX 3.1 and 3.0.
Important Final Notes

So, that’s pretty much it, really. That covers all the different cables that you might need to plug into your power supply unit. I should say that every power supply unit and every brand is slightly different. They might be labeled differently. Always make sure you check the manual if you have any doubt at all, but certainly, things are quite well-labeled. And if you’ve got a modern build, if you’re not using any SATA SSDs or SATA hard drives, and you don’t have anything at the front of your case, you might be able to get away with just connecting the two motherboard pins and then one CPU cable and then a couple of, you know, PCI Express cables if you have a powerful graphics card. Obviously, if you’ve got a CPU with integrated graphics, then it’s even easier because you won’t actually need a PCI Express cable. You literally just have one CPU cable, one motherboard cable, well, two motherboard cables which then come to one end when you plug it in, and that’s it. And that’s actually the beauty of having a modular or semi-modular PSU because you just… otherwise, you’ve got all these cables flowing all out of your PSU, and it’s a nightmare.
But that covers the new ATX 3.0 and 3.1 power supply units, which some people call PCI Express Gen 5, but as I mentioned at the start, that’s not really correct, especially since this new 12V power connector is actually used with PCI Express Gen 4 graphics cards. But I hope you found this video useful. If you did, please click the thumbs up button, and please subscribe to see more videos like this. Thanks for watching!
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