→ Power supply connectors [sata, eps, atx, pcie ...]?

In this article we are not going to limit ourselves to explaining what connectors there are and for which components they are used… We will also talk about what standards define them, their pin distribution, precautions to take into account, current limits and more.

The power supply connectors are a very important part of mounting a PC. In this article, we will basically cover the most used connectors (ATX, CPU, PCIe, SATA, 4-pin Molex and FDD), we will show you their pinout or pinouts and we will give you the most important brush strokes. Let's go there!

Index of contents

24-pin ATX connector

This is the main connector used on motherboards. It has five "special" pins that are not seen in any connector and it is worth commenting:

• Power Good or PWR_OK (8) signal: Seeks to prevent the PC from operating with inadequate voltages by alerting the board that the source is malfunctioning. A signal is generated after the source passes internal tests upon startup. If it takes too long, the source is identified as failing. As this signal is 5V, in low quality sources this output is usually connected to the 5V rail, so that the board believes that it is a suitable PWR_OK signal. 5VSB rail (9): This is the pin dedicated to the 5V Standby rail, which remains active as long as the source is plugged in and with the switch in the on position, including when the equipment is turned off, to supply power to any device that is stay on standby. -12V Rail (14): A fairly unknown rail that is still used by power supplies, but is falling out of use as it was with -5V. Power Supply On signal (16). This signal is responsible for keeping the source on / off as indicated. When we turn on the computer, the signal is activated by turning on the equipment. The source is turned off when the board opens the circuit. It should be mentioned that, to "force" the source to turn on, we can manually close this circuit in a very simple way, by bridging this pin with anything metallic (for example, a clip) from the source COMs. An empty pin (20). Before, in this space there was a pin dedicated to the -5V rail, which no longer exists and is in total disuse.

A couple of decades ago, instead of a 24-pin connector, a 20-pin connector was used. At the beginning of the century (approximately) it was decided to add an additional 4 due to the increase in the consumption of motherboards of the time. Even today, most sources include a detachable 24-pin 20 + 4 connector, so it can be used seamlessly on 20-pin boards. The truth is that any home motherboard of recent years includes a 24-pin connector, we do not know if there are exceptions.

How many should we expect in a modern power supply? Well, one, obviously. Although there are certain models of very isolated sources, such as the Phanteks Revolt X, which include two to be able to power two teams at the same time. The source works when there is a PS_ON signal in one of them and it turns off when there is no longer any of them.

At the end of each connector's explanation, we will answer this question, clarifying how much is expected from a decent source.

CPU connectors: EPS12V and ATX12V

This connector is dedicated solely and exclusively to power the main VRM of the motherboard. That is, a series of components that regulate the 12V voltage that enters the source, to deliver the necessary stable voltage on the one hand for the VCore (the CPU itself) and on the other for the SoC (integrated graphics, integrated memory controllers…)

VRM of a motherboard How many should we expect in a modern power supply? The vast majority bring 1 of 8 pins (4 + 4 pins), but in the higher level there are two to work on maximum performance CPU platforms such as the Intel Core i9-X, or Ryzen Threadripper WX, where they are recommended.

Are 2 EPS required on motherboards?

Many motherboards on the new mainstream platforms (X370, X470, Z370, Z390) include two 8-pin EPS or one eight-pin and one four-pin. This creates great confusion since most users have only one of these connectors, raising doubts about whether it is necessary to use both or spare with one.

We have investigated very intensively to give maximum information on what can go through these connectors. Our references and various professional tests carried out make it clear that up to 300 watts is 100% safe to use and that the voltage drop is not relevant.

We are talking about 6.25A for each 12V pin, while the recommendation of Molex (manufacturer of these connectors) is up to 8A using 18AWG thick wiring (used by almost all sources). So you can speak of total security in the values ​​in which the X470, Z370, Z390 platforms move…

So what is the bottom line? Very simple: It is NOT necessary to use more than 1 8-pin EPS on Z370, Z390, X370 and X470 mainstream platforms. That more than 1 is included seems to respond to a marketing trend.

For maximum performance processors (HEDT) that do not have a large consumption (i9 7820X, 7900X…) it comes with 1 EPS, although for higher options it is recommended to use both, in addition to the fact that one of these CPUs has a source top quality.

Using adapters is a terrible idea. Not only are they totally unnecessary (as indicated above), but there are plenty of very low-quality adapters on the market that burn very easily. So better not to use them.

6-pin and 8-pin PCIe connectors

This connector is the one used in graphics cards with a maximum consumption of more than 75W. The PCIe slot of the motherboard itself is prepared to give this power at most, so those graphics that consume more make use of these connectors to receive auxiliary power. To a lesser extent, they can be seen on certain motherboards, especially high-end ones, and generally with the aim of giving extra power to PCIe slots.

6-pin PCIe auxiliary connector on a high-end motherboard.

According to the PCI-SIG standard, 1 6-pin connector is made to supply 75W and 1 8-pin connector to 150W. In practice, we rather fit the criteria we have given for the EPS connector, where we were talking about a recommendation of up to 300W and a maximum of almost 400W (the latter according to the recommendation of Molex). Analogously, due to having a pin less than 12V, we can speak, as a guide, of 225W of recommendation and 300W of maximum.

This coincides with Seasonic's recommendations in this regard. Many power supplies include two PCIe connectors in a single cable, enough for almost any GPU with a high power consumption, so the manufacturer insists on recommending using two different cables for high-consumption graphics. It would be, for example, RTX 2080 Ti or Vega 64, especially if we overclock them.

It is very difficult to reach the consumption levels mentioned above, but we can conclude one thing regarding this matter:

When using high-end and very high-consumption hardware (Threadripper / i9 X299 CPUs, etc… RTX 2080Ti / Vega 64 GPUs…) it is recommended to use two 8-pin EPS and 2 different PCIe cables, respectively.

In more modest hardware than that, it is not necessary, especially in the case of CPUs on the Intel 1151, AMD AM4 and similar platforms.

Going back to pinouts, many will wonder: What is the point of 8-pin PCIe if you don't add any 12V pin? Well, because in reality, the idea was that one of those additional pins was used as a "sense wire". It is basically a pin that acts as a 'sensor' in such a way that, when the GPU demands more power, it is 'communicated' to the source that adjusts the voltages in order to obtain more precise control. This is somewhat deprecated in most power supplies, which simply do not need it to control the voltages properly, so what manufacturers do is "trap" it with a negative pin, since if it were empty the graph would not work.

How many should we expect in a modern power supply? As it depends on the power of the source, we consider that these should be the requirements (6 + 2 pins):

• 4X0W: 1 or 2, better two 5X0W: two 6X0W: 2 or 4, better four 7X0W: 4, in some cases 68X0W: 61X00W: more than 8

If a source of a certain power does not bring the amount we recommend, it is likely to be of false power (especially very cheap models that promise much more power than the reputed quality alternatives offer)

SATA connectors

This is the connector used in SATA hard drives mainly, but it is increasingly extended to other devices such as liquid cooling, LED controllers, etc. As we can see, it has voltages of 3.3V, 5V and 12V and is not symmetrical, so it is important to look at the correct side for its installation.

The SATA 3.3 standard has been in existence for about 2 years, which requires that the third pin does not supply power to function. Today no consumer hard drive needs this standard so users will have no problem.

How many should we wait in a fountain? Well, at least 4 or 5 divided into two strips, if they go on a single strip there could be problems reaching all the components that we are going to connect. For this reason, it is always preferable to use as many SATA connectors and strips as possible (especially in modular sources), since even if we are only going to use 2 or 3 we may need several strips. Mid-high and high-end fonts typically include 8, 10 or even more.

In the image above we can see AiO liquid cooling that needs to be connected to the source by SATA for its power supply. Note that you must differentiate the SATA power cable from the data cable. The first is only special because of its shape, like the other connectors, not because it performs any special function.

Here you can see, on the left, the female SATA power connector, and on the right the data connector that connects to the motherboard.

Peripheral connectors, the (mis) Molex

Now we go with this misnamed connector, which is usually identified either with the name of Molex connector or peripheral connector. Why is it wrong to say Molex? Well, because all the connectors of a power supply are designed by the Molex Connector Company, so it is not correct to call it that. But it is undoubtedly the most common, in fact it is what we usually call it on the web.

Regarding the functionality of the connector, the truth is that it is gradually falling out of use, as it is hardly needed in some boxes (usually the cheapest ones) and a limited number of devices such as LED lights and others. Most cases, liquid coolers and other devices are using the SATA connector as they are usually included more in power supplies.

What is expected is that a source has between 3 and 5 Molex connectors, few have more than 5 and almost none more than 7 or 8.

The almost obsolete Floppy connector

We end with the Floppy connector, also called FDD or Berg (company that designed them, in this case it is not Molex). It is basically a connector equivalent to the Molex in terms of its pin output but with a smaller size.

Its main use was floppy drives, and currently almost no component uses them (or any more, we say "almost" because we do not know if there is any controller or peripheral that does need it). Generally, fonts come with 1, and fortunately newer ones are limited to including a 4-pin Molex to Berg adapter.

Precautions when using connectors from a source

In general, connecting cables from a source is a quick, easy, and safe process, and the unwritten rule that the connector is the right one where it fits is generally followed. But there are a number of common mistakes in inexperienced users that should be avoided:

• CPU cables and graphics cards are very easily confused, since they are both 8-pin, but in 99% of sources the former are separated in 4 + 4 and the latter in 6 + 2. It is important to distinguish them in this way, or in any case resort to the manual, to the pin distributions that we have taught you, etc., before making the connection so as not to make mistakes. The X connector does not fit into the Y, but some people might mistakenly think it is the correct connector, and force it in, breaking it and with possible consequences that could damage the equipment. The orientation of the SATA connectors can cause the plug to break. hard drive, so if it takes too much force to connect, the orientation is probably wrong. Keep an eye out.

Recommended length of cables from a source

It's not just about getting the right number of connectors, but also about having cables of sufficient length. We have checked the data from various mid-low and mid-high range sources to give an approximate value of what should be expected.

• ATX cables are usually between 550 and 600 millimeters. In this case, it is very difficult for there to be space problems since almost always there is excess length. In the case of CPU cables, you can expect between 550 and 650 millimeters, but the first measure could be short in some PC configurations. Yours is to bet at least 600 millimeters. For PCIe cables, it is also usually around 550-700mm and there are usually no space problems. In the case of cables with double connectors, the second one is almost always around 100mm apart . SATA and Molex cables usually have an initial length of about 400mm and a spacing of approximately 100 or 120mm.

Connectors on modular sources

Modular sources have connectors on the source side, not just the component side. If you want more information about this type of source, we recommend this article, but even so, here we will briefly comment on the characteristics of these connectors.

The most relevant thing to mention is that there is no universal standard for these, so mixing cables from different modular sources is dangerous. In most cases, as you can see in the photo above, Molex connectors very similar to those of the components are used. In general, despite the similarities there is hardly any room for error so as long as you are careful (and consult the manual if necessary) there will be no problems.

On the other hand, other sources such as the one we see above make use of visibly different connectors, clearly distinguishable from those seen in components.

It should also be borne in mind that many brands have a universality between the modular connectors of their power supplies, as is the case of Corsair (which has a list of compatibility and breaks down the connectors by "Type 3", "Type 4 ″…) Or Silverstone (where almost all your fonts have the same compatibility).

In any case, it is always advisable to inform yourself very well in case you need a replacement for modular cables, or when buying wiring kits with “sleeving”. Using the wrong cables can lead (in the worst case) to the source or some component to stop working. In case of custom sleeving, you have to know the specific pinouts (pin schemes like the ones shown above) for each source. There are usually modders who check and publish them on the internet.

Final words and conclusion

We finish our article with a comparative table to make the function of the different connectors as clear as possible.

	ATX	EPS / CPU	PCIe	SATA	4-pin peripherals
Present voltages	12V, 5V, 3.3V, 5VSB, -12V,	12V	12V	12V, 5V, 3.3V	12V, 5V
No. of pins	24 (formerly 20)	8 (generally separable into 4 + 4)	6 or 8 (almost always 8 separable in 6 + 2)	fifteen	4
Connects to...	Motherboard	Motherboard	Graphics cards that require it, some motherboards (very minority)	Hard drives, now also used in controllers, liquid cooling, etc.	LED drivers, rehobúses, boxes, etc…
Normally feeds	PCIe motherboard and slots	Entirely to the on-board VRM dedicated to CPU	Graphics cards	Hard drives	LED drivers, rehobúses, boxes, etc…
Peculiarities on maximum power	Nothing to highlight	It is recommended to use 2 connectors on CPUs of + 300W, in <300W it is not usually necessary. AM4 and 1151 platforms are not necessary.	It is recommended to use two CABLES in high consumption graphics, especially with OC. We recommend max 225W per cable.	AVOID adapters used to power graphics cards or other high-consumption components.	AVOID adapters used to power graphics cards or other high-consumption components.

Power supply connectors are a world and it is very important to know how to use them correctly, understand how they work and what they supply, and what their voltage outputs are. The latter was very easily identifiable in the past, since the norm was that the sources included colored cables that indicated the corresponding voltage. Now the overwhelming majority of decent sources have 100% black cables, so these pinout images are relevant for when we need it.

We recommend reading our updated guide to power supplies and other interesting guides:

• What is a modular source and what is its importance The different formats in power supplies Passive power supplies, pros and cons

We hope that all the information in this article has been useful to you, and we invite you to participate in the comments with all your suggestions, doubts and even any constructive criticism you may have. See you!