Just realized how much a bad PSU can fake other symptoms

Had a client's PC at my shop last Tuesday that kept randomly restarting under any load. I was chasing RAM errors, driver issues, and even swapped the motherboard before I finally threw a multimeter on the 12v rail. The voltage was dropping to 11.1 during a CPU stress test. Anyone else ever waste a full day on a problem that turned out to be the power supply?

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kim.stella4mo ago

Ugh, the 11.1v reading is a dead giveaway. I actually keep a digital multimeter in my tool bag now for exactly this reason. The worst part is when you're swapping parts and the system seems to work fine in BIOS or at desktop but crashes as soon as you actually push the GPU or CPU. I had a similar situation where I replaced the whole build's RAM and SSD before I finally tested the rails. Multimeter is cheaper than a new motherboard and way faster than blindly swapping parts. People sleep on how voltage ripple can also cause weird system instability that looks just like a bad driver or memory corruption.

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lisa6714mo ago

11.1v" holy crap, @kim.stella that's brutal. I'd be losing my mind if I went through all that just to find out it was the PSU the whole time.

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