I have a couple servers in my garage running ESXi. Each server has a 1000W gold rated PSU which I bought second hand from a miner. They work great and were pretty cheap. These are not super powerful machines, but they each have 4 DIMMs, 4-5 HDDs, and an old (somewhat power hungry) AMD GPUs (5850 and 7780 IIRC).
I am now looking to purchase a UPS to protect these servers in case of a power outage.
Please understand that I am not looking for shopping advice, my questions are not related to a particular model/brand. With that in mind, I have two related questions:
Given that each server has 1000W PSUs, but run on average much lower (300-400W, saw it peak once at 500W, but should not be more). What is a good size for the UPS? I am not interested in keeping the servers running in case of an outage and 5 minutes should be plenty of time to stop everything.
I have sometimes observed that the fuse was tripping (this is the garage, so the electrical installation is not very good) when both servers are rebooted at once. I assume this is because the PSU is running at peak for a few seconds when powered on (is that possible/true?). If so, is that a concern for my UPS? For instance, if I get a 1200VA UPS, will it get in trouble when the power returns and both servers come back up at once? If so, what would be a solution? I do not feel like purchasing a super expensive UPS, so would it be an option to simply get lower wattage PSUs? Any better (i.e. less expensive) options?
Thanks in advance for your help!