Which one is the culprit: Mobo or Power Supply?

Question

Seriously, I need to find out. Usually, I have sufficient motherboards and power supplies to try swapping out one for the other (did the problem move or cease to exist?). Unfortunately, I am down to my last odd motherboard and last odd power supply. The good news, of course, is that the better half is happy that my "techie junk" has diminished substantially! But, I digress.

Mobo: Biostar NM70I-1037U Mini-ITX with Dual-core Celeron 1037U processor

Worked successfully 1 year ago with another power supply and then it and the RAM was put safely away (sealed in plastic).

Power Supply: Mini-Box picoPSU-160-XT High Power 24 Pin for Mini-ITX (small-ish)

Worked successfully 6 months ago with a different mobo and then it was put safely away (sealed in plastic).

Today, I completed a build with the mobo, power supply, a Thermaltake Cube V1 enclosure (includes a case fan), RAM (previously sealed sway), CPU fan (supposedly not needed according to Biostar but I am paranoid), and an SSD. I attempted to power up with 2 different AC/DC power adapters:

12V, 5A
19V, 2.1A.

1. Observed symptoms with a 12V 5A AC/DC adapter

Push power button.

    Loop forever         Both fans and power indicator light on for 1 second         Both fans and power indicator light off for 2-3 seconds     End of loop

2. Observed symptoms with a 19V 2.1A AC/DC adapter

Push power button.

Power light comes on and stays on forever.

Fans do not activate.

Is it the mobo or the power supply?

Opinions, please.

Also, suggestions for further testing, aside from sticking the suspect power supply in another build which I don't have at the moment?

Thank you in advance.

clem57 · Accepted Answer

Looking at picoPSU-160-XT, 160watt (200watt peak) , 12V input DC-DC ATX Power Supply , they suggest a 12V 12.5 A AC-DC switching supply. The other thing a noticed is a 4 square plug for power on the Biostar board. Did you plug into that?

Clem

Robert Peter Oakes · Answer

try and open the whole thread in a new tab, I find some where you can addto in the main thread (Mail) wont let you edit unless you are actually in the main flow only

jw0752 · Answer

Hi Richard,

I don't know why but your symptoms sound like a power supply that is trying to power up but is exceeding a current limit and shutting itself back down. Often these will automatically try to restart after a few seconds and this causes a kind of endless loop of on and off. Try powering the power supplies without the computer attached. Check the voltages with a meter. See if the power supplied by the power supply continues to hold with a 5 amp load. Use a bench supply to power the computer and slowly bring the voltage up to 12 volts while watching the current level. Try your power up with the fans detached. Use and ohm meter to look at the impedance of the power input of the computer. Any chance that you have polarity reversed on the computer? Just some ideas.

John