The CPU restarts during a brownout. What can be done to avoid this?
The CPU restarts during a brownout. What can be done to avoid this?
I own a reasonably good APC UPS (APC Easy UPS BVX1200LI-MS). It's a 1200VA unit rated for 600W. The CPU is a Ryzen 9 9700x with an RTX 3080, all driven by Corsair SF750 750W Platinum PSUs.
If the PSU calculator was accurate, the entire setup should stay within 600W of maximum draw.
My setup operates in an area with frequent brownouts—usually brief and only affecting my room light slightly. When idle (browsing or typing), everything functions normally without resets, black screens, or issues. However, during intense tasks like gaming, rendering, or compilation, the system shuts down due to brownout or minor voltage fluctuations.
What actions should I take? Could installing a voltage stabilizer before the UPS improve stability?
Try the highest possible stress levels for GPU/CPU together (if your system can manage).
Disconnect the UPS.
If it remains active for a few minutes, other issues might be involved; otherwise, upgrade to a larger UPS.
It remains active for 3-4 minutes when operating at full capacity with the UPS disconnected from the outlet. When the voltage decreases, I notice a clicking sound from the UPS, coinciding with the PC shutting down, leading me to believe the UPS is the issue now. My new power supply was purchased just two days ago due to concerns about frequent shutdowns. The previous unit was a DeepCool PM750D (750W Gold). After replacing it, the shutdowns persist.
The runtime of about 3 to 4 minutes seems quite short. Does this UPS model include software and the capability to issue a shutdown command to the PC through a USB connection? I really think this backup unit might be too weak for the system. Other factors include its age, especially the condition of its batteries. Many of these use lead-acid batteries, and if the system is older than three years—or even after five years—the batteries lose a significant amount of capacity during that time.
The optimal choice is a double conversion UPS that provides stable voltage output. Its internal conversion ensures consistent power regardless of whether it draws from battery or mains. I rely on APC Smart-UPS ONLINE models for my home devices. They are available used—commercial units without batteries—to cut shipping expenses, after which I purchase replacement batteries.
The RTX 3080 is frequently mentioned for its ability to generate power spikes above 500 watts. Nvidia suggests using a power supply around 750W for optimal performance.
Unfortunately, the Corsair SF750 suffers from a notably short hold-up duration. This is one of the lowest I've encountered in reviews. According to the ATX specifications, the hold-up time should reach at least 17ms (possibly 18ms). The SF750's 'AC loss to power OK Hold Up Time' signal measures only 8.8ms. It's no surprise your system shuts down during brownouts. Refer to Tom's SF750 review for more details. This product's weakness lies in its insufficient hold-up time, attributed to the compact bulk capacitor in the APFC converter. While the power OK signal remains precise, its strength is limited. The sound you detect from the APC UPS originates from the relay transitioning from mains to inverter output. The startup of the inverter and subsequent relay action take a finite period. When your computer is idle, the bulk capacitor within the ATX PSU might retain enough charge to sustain operation. However, if the PC is under heavy load, the capacitor discharges more rapidly, potentially depleting before the UPS inverter begins and the relay activates. For continued reliability of the APC UPS, consider replacing the SF750 with a PSU offering a significantly longer hold-up time. High-quality PSUs typically surpass 20ms. Could your case accommodate a standard ATX PSU rather than an SFX unit? You'll have a broader selection to explore.