How to Test Your Computer’s PSU With a Multimeter

How to Test Your Computer’s PSU With a Multimeter


Someone testing the pins of an ATX power connector with a multimeter.
Jason Fitzpatrick

If you have a digital multimeter on hand, it’s very uncomplicated to examination your PSU and rule out ability gremlins as the source of your personal computer complications.

Why Use a Digital Multimeter?

Standalone PSU testers are wonderful and we constantly have a person on hand to get brief final results. They can even give you handy values like the Power Excellent (PG) value that exhibits you how rapidly your PSU will come up to total power—that’s a little something a multimeter simply cannot do.

But plenty of persons have digital multimeters on hand already and really don’t have a PSU tester lying all over. So even though it is pleasant to have a PSU tester for those tiny extra functions like the PG value, you can get virtually all the identical info with a extra fingers-on tactic employing a multimeter.

How to Take a look at Your PSU with a Electronic Multimeter

Although employing a multimeter is a little bit much more fingers-on than just plugging in a PSU tester, it is beautifully protected if you follow some basic guidelines.

Warning: At no stage will we be opening up the PSU by itself. Accomplishing so devoid of proper safety measures, knowledge, and applications can give you a deadly shock.

Right before continuing, we want to emphasize a couple points. 1st, testing the output of your PSU applying the techniques outlined down below is quite harmless. Opening up the real PSU to access the “guts” of the device is not and will expose you to both line-level electricity coming from the wall and to the capacitors in the PSU. Touching the completely wrong issue within the entire body of the PSU has the probable to prevent your coronary heart.

If your PSU is malfunctioning, the safest thing to do is merely swap it. Trying to swap big capacitors, transformers, or other internal PSU elements is an advanced electronics restore and barely worth it, specified how fairly reasonably priced PSUs are.

Familiarize Your self with the ATX Pinouts

Just before we proceed, let’s consider a peek at the 20/24-pin connector to familiarize ourselves with the format and the expected voltages.

We utilised a handy pinout planner made by Reddit person /u/JohnOldman0 to make the diagram underneath and advise the tool for anyone scheduling a personalized cable task.

a 24-pin ATX connector with voltage labeling.

If you are keeping the connector with the clip up, the numbering scheme starts off on the bottom left, reads 1-12 on the base row, and then 13-24 on the leading row, for a 24-pin connector. For the purpose of this write-up, when we use the expression “top” we necessarily mean “clip up.”

For a 20-pin connector, it’s 1-10 and 11-20, respectively, however it is really worth noting that the spot of the precise voltages doesn’t change even if the pin amount does. The regular 24-pin ATX connector simply adds an more 4 pins onto the 20-pin connector while preserving the initial structure.

Power Down The PSU

If your PSU has a swap, transform it off. If it is run on instantly when connected to an outlet, unplug it.

Either way, you want the energy off PSU—not just flip off your computer—before continuing to the next steps.

Disconnect the Part Cables

You do not have to take away your PSU from your Computer if you’re seeking to troubleshoot the PSU in position, but you should really disconnect all the ability potential customers (not just the just one you are screening) to enjoy it safe and sound.

Even though it’s not likely things will go so erroneous as to damage adjacent components while you exam a certain cable, there’s no motive to hazard it when it only can take a few seconds to get rid of the power prospects to your GPU, drives, and this kind of.

Jumper the Electric power On Pin

The initial pins you need to pay awareness to are the electrical power source on pin and the adjacent grounds. You need to have to bridge the electricity supply on pin (which is pin selection 16 on the 24-pin readout, fourth from the left on the best) to the floor pin on both facet, as witnessed in the ATX pinout diagram earlier mentioned.

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A PSU power cable with a jumper across the power on and ground pin.
Jason Fitzpatrick

You can soar the 16 pin possibly to the 15 or the 17 pin (both equally of which are ground pins). In the image previously mentioned you can see we’ve jumped the 15 and 16 utilizing a limited duration of paper clip bent in a U-form. The absence of insulation listed here isn’t a huge offer as the jumper only carries 24 volts and you won’t be touching it throughout the test.

You can also use scrap piece of 18AWG or 16AWG wire. There’s also easy ATX 24-pin PSU jumper bridge resources.

The bridge resource has minor numbers stamped on it for every single of the pinout places, which is practical if you want a obvious indicator which pin is which with no counting. (However be forewarned that some multimeters have probes just a smidge also limited to reach by means of the bridge, which would make it challenging to tap the pins and test the voltage.)

Switch the PSU On

Once you have jumpered the electrical power on pin to a floor pin, turn the PSU back on. You need to listen to and see the enthusiast spin up on the PSU. Some PSUs element admirer that only briefly spins up all through the electric power-up system and then is established to idle until the PSU temperature rises—so really don’t be alarmed if the lover spins and then stops a number of seconds afterwards.

Tests the Pins with Your Electronic Multimeter

Testing your PSU with a electronic multimeter isn’t wildly various from applying a PSU tester, the most important distinction is that alternatively of a minor microchip doing the calculations and supplying the thumbs up or thumbs down, you get the hands-on expertise of currently being the microchip and deciphering the facts oneself.

At this point, you require to flip on your multimeter and set the reading through to DCV. If your multimeter is “auto-ranging,” there is no will need to do anything at all, if you have to have to established a vary set it to 10V.

Set the black multimer probe on any of the grounded pins. For a common 24-pin ATX connector, which is pin 3, 5, 7, 15, 17, 18, 19, or 24. We’ll be utilizing pin 15 due to the fact its area right adjacent to the electric power jumper means it is effortless to recognize.

With the black probe on a grounded pin, touch it to any other pin and validate that the readout is as predicted.

For example, if you floor out on pin 15 and contact pin 12, the readout really should be 3.3V (or within just ±5% of 3.3V). You can see in the photo above that our 15-pin to 12-pin relationship is useless on with a 3.3V readout.

Repeat this approach for all the pins, confirming that the voltage readout is inside the acceptable range. If the values aren’t within variety, it is time to exchange the PSU. Here’s that ATX electric power connection pinout yet again, for reference.

a 24-pin ATX connector with voltage labeling.

And listed here are the pinouts for the 8-pin (4+4) ATX/PCIe, the 8-pin (6+2) ATX/PCIe, and the Molex travel connector if you’d like to take a look at these pins as well.

PCIe and Molex connectors with a voltage reference chart.

Like with the larger 24-pin energy connector, merely floor out your black multimeter probe on a recognized floor (any of the black pins previously mentioned) and then contact the pink probe to the other pins to check their voltage. You need to check out them for the exact ±5% array.

In the interest of preserving your components, we’re not even going to advise wiggle room parameters in this article. If a single or far more of the readouts are exterior the ±5% range, just switch the PSU and save by yourself the complications that occur from a failing power provide.

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