# Thread: Using a multi meter to find out voltag regulation

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## Using a multi meter to find out voltag regulation

I checked the PSU FAQs about how to determine voltage regulation using a multi meter but it doesn't explain where do I test it at. I am wondering if someone knows or know about a video doing this

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Should I have the PC turn on with everything on and use a spare molex/pci cable to measure the voltages of the 12v, 5v, 3.3v rail idle load and under load?
Is that a way of doing it?

3. Originally Posted by faircomposer15
Should I have the PC turn on with everything on and use a spare molex/pci cable to measure the voltages of the 12v, 5v, 3.3v rail idle load and under load?
Is that a way of doing it?
Yes.

Find a spare connector and stick the DMM probes into it. For +5V, you can use a Molex. For +12V you can use a Molex, PCIe or CPU power connector that's not in use.

Turn the PC on and see what the DMM says the voltages are.

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You can stick the probe through the back of the 24-pin motherboard connector, next to the wires. That's where you can find 12V, 5V, and 3.3V.
Black probe goes to ground (black wire).
Red probe goes to the voltage you want to test - yellow = 12V, orange = 3.3V, red = 5V.
Just be careful working inside a live computer.

If you just want to test 12V and 5V, the molex connector is easy to use. The two inside pins are ground. The outside pins are either 12v or 5v.

I suggest not using a sata connector... easy to short some pins.

And you should test while at full load and idle load. Voltages should be within 4% of nominal (IMO), and voltage should deviate less than 200mv from idle to full load.

5. Be sure your meter is in voltage mode and not current.

I have a meter that only does volts, to avoid my making the mistake.

This guy illustrates
https://www.bing.com/videos/search?q...5&&FORM=VRDGAR time 3:07
Last edited by ashiekh; 01-13-2019 at 02:56 AM.

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Thanks guys, I am also wondering if you guys have any software that can put load on the system?

7. Originally Posted by faircomposer15
Thanks guys, I am also wondering if you guys have any software that can put load on the system?
There's lots of benchmarks out there.

8. Originally Posted by Rexper
You can stick the probe through the back of the 24-pin motherboard connector, next to the wires. That's where you can find 12V, 5V, and 3.3V.
Black probe goes to ground (black wire).
Red probe goes to the voltage you want to test - yellow = 12V, orange = 3.3V, red = 5V.
Just be careful working inside a live computer.
I just don't like this method because it requires you to hold the probes in place while the PC is running.

Probes typically fit very nicely inside Molex pins.

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this is the way i did it.....its easier to just buy the tester, its cheap

https://www.wikihow.com/Check-a-Power-Supply

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Originally Posted by jonnyGURU
I just don't like this method because it requires you to hold the probes in place while the PC is running.

Probes typically fit very nicely inside Molex pins.
Atleast with my connector the probes fit snug, no need to hold the probes in place.
It's probably the best method for testing the 3.3V rail aswell, otherwise I prefer molex.

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