If you are using an UPS rated as 750VA or even less with an APFC PSU rated at 600W or more and it has been working just fine when switching to battery, and it continues working for a year at least, then please, please, let me know the brand and model of your UPS.
The long story.
I wanted a silent UPS (no fans when working from mains) for my workstation / media PC / occasional gaming PC.
So, I got my kill-a-watt measured the real max power use of the system during various stress tests (3D Mark Demo, Cinebench...). It turned out to be always less than 250W, which is expected for a mediocre non-gaming system with i7-7700 CPU and GTX 960.
The problem is that my PSU is an active PFC unit rated at 620W (an overkill for my case but I thought that a PSU with some redundancy is a better choice - more powerful components etc.). And I've heard that APFC units can trigger high inrush current when a UPS is switching to battery, especially a UPS with simulated sine.
It usually is not a problem for UPSes that are rated well above the max power of the PSU. For example, 1000VA, 1500VA might work just fine. Although not suggested, but still I might be fine with a simulated wave unit.
But there's a catch. In my country the only reputable UPS brands available are Eaton and APC. I have heard lots of complaints about APC Back-UPS (and Pro) units lately (dying too soon, someone bought 15 of them and only 8 survived after warranty). I was looking at BR900GI and reading reports of its premature deaths on APC forums, and APC response was that it would be a mistake to use Back-UPS with an APFC PSU, and that might be the cause of the damage. I'm not so sure if this is true or just an excuse. Anyway, after reading those stories I'm afraid to buy BR900GI (or any other of the same series).
So, considering APCs response, I should buy a SMT UPS with a sinewave. And calculating the full power of the PSU (620W) I would need to buy at least SMT1000I, which is very expensive.
I really would like to get by with SMT750I (and even that would be an overkill because I don't need those "smart" features), but I'm not sure if SMT750I also would not suffer from overload caused by the 620W PSU, even if the real consumption is just 250W max.
My other options are Eaton Ellipse Pro (simulated sine) and 5SC (pure sine). They have generally good reviews ... except complaints about fan noise in their 1000VA and up models since 2016, when Eaton made the fan always spinning, even when idle. So - no solid, silent UPS from Eaton at this time, unfortunately. Some people voided their warranty and replaced the fan with Noctua, but I'm not quite ready for that.
I also tried an AEG Protect B 1000 (true sine) and it worked fine on my system, but I had to return it because of pretty high non-stop fan noise. And also I read some service reports about the consumer grade UPSes from AEG - they are saving costs on battery charger transistors, picking ones that have just 10% reserve, and as a result, services often see these units coming in with burnt charging transistors. And APC lower end is no better.
And I have no true sine Cyberpower units in my country.
So, my current only choice seems to be SMT750I, but I'm not sure if it's worth trying and that's why I wanted to know is somebody else has done that and if it works reliably. Of course, you can never guess and every UPS-PSU combination might behave differently, but still it would be encouraging to know that at least some people have no issues. I just don't want to buy a 1000VA UPS for a system that is never going to normally consume more than 250W.
The long story.
I wanted a silent UPS (no fans when working from mains) for my workstation / media PC / occasional gaming PC.
So, I got my kill-a-watt measured the real max power use of the system during various stress tests (3D Mark Demo, Cinebench...). It turned out to be always less than 250W, which is expected for a mediocre non-gaming system with i7-7700 CPU and GTX 960.
The problem is that my PSU is an active PFC unit rated at 620W (an overkill for my case but I thought that a PSU with some redundancy is a better choice - more powerful components etc.). And I've heard that APFC units can trigger high inrush current when a UPS is switching to battery, especially a UPS with simulated sine.
It usually is not a problem for UPSes that are rated well above the max power of the PSU. For example, 1000VA, 1500VA might work just fine. Although not suggested, but still I might be fine with a simulated wave unit.
But there's a catch. In my country the only reputable UPS brands available are Eaton and APC. I have heard lots of complaints about APC Back-UPS (and Pro) units lately (dying too soon, someone bought 15 of them and only 8 survived after warranty). I was looking at BR900GI and reading reports of its premature deaths on APC forums, and APC response was that it would be a mistake to use Back-UPS with an APFC PSU, and that might be the cause of the damage. I'm not so sure if this is true or just an excuse. Anyway, after reading those stories I'm afraid to buy BR900GI (or any other of the same series).
So, considering APCs response, I should buy a SMT UPS with a sinewave. And calculating the full power of the PSU (620W) I would need to buy at least SMT1000I, which is very expensive.
I really would like to get by with SMT750I (and even that would be an overkill because I don't need those "smart" features), but I'm not sure if SMT750I also would not suffer from overload caused by the 620W PSU, even if the real consumption is just 250W max.
My other options are Eaton Ellipse Pro (simulated sine) and 5SC (pure sine). They have generally good reviews ... except complaints about fan noise in their 1000VA and up models since 2016, when Eaton made the fan always spinning, even when idle. So - no solid, silent UPS from Eaton at this time, unfortunately. Some people voided their warranty and replaced the fan with Noctua, but I'm not quite ready for that.
I also tried an AEG Protect B 1000 (true sine) and it worked fine on my system, but I had to return it because of pretty high non-stop fan noise. And also I read some service reports about the consumer grade UPSes from AEG - they are saving costs on battery charger transistors, picking ones that have just 10% reserve, and as a result, services often see these units coming in with burnt charging transistors. And APC lower end is no better.
And I have no true sine Cyberpower units in my country.
So, my current only choice seems to be SMT750I, but I'm not sure if it's worth trying and that's why I wanted to know is somebody else has done that and if it works reliably. Of course, you can never guess and every UPS-PSU combination might behave differently, but still it would be encouraging to know that at least some people have no issues. I just don't want to buy a 1000VA UPS for a system that is never going to normally consume more than 250W.