I can't find anything about this PSU other then its common in Acer rebuilds so I cant speak to the quality. But usually the PSUs used by the big PC makers are sufficient for the systems specs as
they are shipped, but that doesn't mean the PSU hasn't failed in some way which is common for cheap PSU's
Seeing on how the PSU is having a power issue I still think the best first option would be to replace the power supply and good news is that appears to be a standard ATX power suppl so it should be easy enough to replace.
This would be a good option
https://pcpartpicker.com/product/Q7...onze-certified-atx-power-supply-cp-9020120-na
You could also try and buy a PSU tester, usually between10-20 USD on Amazon such as this
https://www.amazon.com/HDE-Power-Supply-Tester-PCI/dp/B005UZHB6G . You then want to unplug all the PSU cables from your motherboard and test them all with this.
Again I can't say it's not something else but this would be my first step.