Question : Problem: UPS Ac input voltage problem or internal PC Power supply problem?

We have a computer that shuts down every 2 days or so, symptomatic of a bad power supply. But we also have AC Input voltage, from the wall outlet, that fluctuates between 109 and 118 in a 4 minute period. The computer is connected to an APC 500 es UPS, and the voltmeter shows the same fluctuation in the battery side of the UPS, where the computer is plugged in. In other words, this UPS does not regulate the ac voltage. We haven't checked out the internal pc power supply yet, because we have a suspicion that the ac input voltage to the PC is the real culprit. Could this suspicion be true? Note: My apologies if this question has already been answered, could not find a clear-cut answer. DOES AC INPUT VOLTAGE IN RANGE 109-118 cause problems?

Answer : Problem: UPS Ac input voltage problem or internal PC Power supply problem?

Those checkers only check DC volts in a basically unloaded condition.
- Unloaded is not where problems happen.
And the response time is WAY to slow to see any kind of ripple or noise problems in the output.

They are good to tell for sure if a is PSU is bad... (as in REAL bad)
.... but they don't tell for sure if a is PSU is good.

For that you need to load it up around 80%-95% and to use an oscilloscope.

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