My CyberPower OLS1000EC UPS sometimes cuts power when my PC restarts, especially during quick transitions such as entering MSI M-Flash from the BIOS. The PC uses a Ryzen 7 7800X3D, Radeon 9070 XT, and a 750 W Deepcool PN750M PSU; its measured peak consumption is about 450 W, while the UPS is rated at 1000 VA. The behavior is intermittent, but the computer works normally when connected without UPS protection. Could the PSU's inrush current during a rapid restart be triggering the UPS's protection circuitry? I also replaced the PSU's original 16 A power cable with a 6 A cable because the system draws roughly 2 A at 230 V. I need to flash the BIOS and am concerned that the UPS might cut power during the restart after the BIOS has finished writing. Is it safer to use the UPS, its mains-bypass mode, or connect directly to mains power?
2 Answers
First test whether the issue is caused by the UPS at all: run the same restart sequence with the PC connected directly to mains, or use the UPS’s bypass mode if that passes utility power straight through. Since the PC behaves normally without the UPS, the UPS, its configuration, or its battery/protection system is the likely area to investigate. Also confirm that the battery is properly connected and healthy, even if the unit is new. I would not start a BIOS flash until the power path is reliable, because losing power during the write can leave the motherboard unusable.
The lower-rated cable is probably not the explanation by itself—the computer’s actual current draw is well below 6 A—but using the original, correctly rated cable is still the sensible choice while troubleshooting. Avoid relying on an unstable UPS during the update; test the exact restart behavior first and use the most stable power source available.

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