I was running Ollama with a 65,536-token context window through Zoo Code in VS Code, asking it to analyze a folder of relatively simple code. After about 4–8 minutes of heavy processing, I heard a loud bang. The PC was still running, but the UPS had switched to battery mode and would not return to mains power. Inspection showed that the UPS fuse had blown apart.
The PC has a Ryzen 5 7600, RX 7600, 16 GB of DDR5 RAM, and an XPG 650 W power supply. The UPS is a Ragtech 1200 VA model.
Could the high CPU and GPU usage from running the local model have overloaded the UPS, or is this more likely a failing UPS, power-supply fault, or electrical problem? Is it possible that the incident damaged the PC even though it still appears to work normally? I also want to know whether it is safe to continue using local AI workloads with this setup.
4 Answers
Remember that the PC's power supply rating is its maximum output, not necessarily what it constantly draws. The PSU also consumes more power than it delivers because of efficiency losses. For example, delivering 650 W at 85% efficiency would require roughly 765 W from the UPS. That does not prove the PC reached that level, but you should check the UPS's actual watt rating and measure the system's real draw rather than relying only on the VA number.
The timing may be related because the workload increased power demand, but it could also be coincidence. The PC can appear fine after a UPS failure, especially if its own PSU handled the event, but hidden damage cannot be ruled out from observation alone. Check the PC power supply and UPS specifications, inspect for unusual smells or noise, and avoid further testing with the suspect UPS until it has been cleared or replaced.
The model itself is not electrically different from any other demanding application. The likely factor is that it may have driven the CPU and GPU harder, increasing the system's power draw. A 1200 VA UPS does not necessarily support 1200 watts; depending on the model, its real limit may be around 600–720 W. If the UPS was already old, degraded, or operating near its limit, the load could have exposed the problem.
A fuse blowing can happen from an overload, but a fuse that physically explodes also makes a defective UPS, internal short, aging components, or a mains-side fault plausible. Do not keep using the UPS just by installing another fuse. If a correctly rated replacement fails immediately, there is almost certainly a hardware fault. Have it inspected or replace it, and verify the replacement fuse matches the manufacturer's specification.
The computer did not shut down because of the model; I shut it down normally after discovering the UPS problem. It has continued working normally since then.