Can I use a 900W UPS with a 750W PSU?

Just a heads up, if you have a multi-monitor setup, you need to include those watts in your total. But honestly, if you only need one monitor powered, you should be alright. Just keep saving your work!

It's important to focus on your actual power draw rather than just the PSU's rating. You might want to check your PC's full load with a power meter to see its real consumption. Generally, a 900 VA UPS can only handle around 550W for a short time. If your PC is idle, it could last longer, like half an hour, with lower power usage. You can usually find calculators on UPS manufacturer websites to help you figure out the best match for your setup.

You should be fine! Most people never actually draw the full 750W from a 750W PSU. A typical 750W PSU runs at about 85% efficiency, meaning it can handle around 882W, but don't forget to add the monitors and other devices into that equation. You likely won’t max out your components unless you have high-end parts like a Ryzen 9 and the latest GPUs.

Definitely verify if you're looking at 900 watts or just 900 VA—there's a big difference. If your UPS is rated at 900 VA, it may not fully support your 750W PSU; it might only deliver around 500-600W. If you're doing light tasks like browsing or writing, it might work temporarily, but you'd need to save everything quickly when the power goes out. Good luck!