Question New PSU makes UPS click on startup - - - is it overloaded ?

[GreenPan]

I just got an ASRock PG-1300G PSU for my 5090 GPU. I ran it at full load with Furmark for 10 minutes and played Helldivers 2, everything seemed fine. But I notice that when I press the power button to turn the PC on (when it's totally off), my UPS clicks and the display lights up almost like it was momentarily overloaded. Is that odd? My previous power supply didn't do that and I'm not sure what to make of it.
The UPS has a max load of 900W

 

[Lutfij]

My previous power supply didn't do that and I'm not sure what to make of it. The UPS has a max load of 900W
Make and model of your UPS and it's age? Make and model of your PSUY prior to the ASRock PG-1300G?

Moved thread from Components section to Power Supplies section.

 

[Misgar]

when I press the power button to turn the PC on (when it's totally off), my UPS clicks and the display lights up almost like it was momentarily overloaded. Is that odd?

Not really. Quite a few ATX PSUs momentarily draw up to 100A from the AC mains at initial switch on, especially from a nominal 230V 50Hz supply. Even from a nominal 115V 60Hz mains supply, the switch-on surge can be tens of Amps.

With a large PSU like the PG-1300G rated at 1300W, it's possible the switch on surge is too much for your old 900W UPS.

By the way, what is the VA rating of your UPS? I'd expect it to be roughly 1500VA if it has a 900W output, as per this APC unit:

https://www.se.com/uk/en/product/SM...usb-and-serial-communication-avr-graphic-lcd/

 

[GreenPan]

Not really. Quite a few ATX PSUs momentarily draw up to 100A from the AC mains at initial switch on, especially from a nominal 230V 50Hz supply. Even from a nominal 115V 60Hz mains supply, the switch-on surge can be tens of Amps.

With a large PSU like the PG-1300G rated at 1300W, it's possible the switch on surge is too much for your old 900W UPS.

By the way, what is the VA rating of your UPS? I'd expect it to be roughly 1500VA if it has a 900W output, as per this APC unit:

https://www.se.com/uk/en/product/SM...usb-and-serial-communication-avr-graphic-lcd/

It's this model: https://www.apc.com/us/en/product/B...bcategory-id=88975&selectedNodeId=27590292604

Interestingly, it hasn't been doing it now. Everything starts up normally. But from what I can tell 900W is as high as you can go with UPSs unless you want to spend huge amounts on units with loud fans that run constantly

 

[GreenPan]

Not really. Quite a few ATX PSUs momentarily draw up to 100A from the AC mains at initial switch on, especially from a nominal 230V 50Hz supply. Even from a nominal 115V 60Hz mains supply, the switch-on surge can be tens of Amps.

With a large PSU like the PG-1300G rated at 1300W, it's possible the switch on surge is too much for your old 900W UPS.

By the way, what is the VA rating of your UPS? I'd expect it to be roughly 1500VA if it has a 900W output, as per this APC unit:

https://www.se.com/uk/en/product/SM...usb-and-serial-communication-avr-graphic-lcd/

Nevermind it just did it again lol

It seems to happen randomly but there must be some trend. It makes the UPS switch from outlet power to battery power just for a moment. I'll also note that the lights sort of flicker


I live in a brand new house so the electrical system should be fine to handle this much

 

[dingo07]

Does it happen if there's nothing plugged into it? What if you were to have the computer plugged into the wall and nothing plugged into the UPS...

Did you change any of the settings in the UPS?

 

[Misgar]

"It makes the UPS switch from outlet power to battery power just for a moment. I'll also note that the lights sort of flicker"

Not surprising the room lights sometimes flicker. Some ATX PSUs momentarily pull a very high current out of the wall socket (and through your UPS) at switch on.

Some PSUs are worse than others. I couldn't find current surge figures for your 1300W unit, but here is a cheap 550W PSU that pulls a hefty 86.31A from a 230V AC input (my mains is 240V). The switch on surge is usually lower for 115V AC supplies, but can still be quite large. With any luck, your Asrock PSU will have a better designed inrush current limiter.

https://www.tomshardware.com/reviews/xpg-pylon-550w-power-supply-review/2

Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. A large enough inrush current can cause circuit breakers and fuses to trip. It can also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current a PSU has right as you turn it on, the better.

It's good to see your APC UPS is rated at 1500VA/900W. I doubt you'll ever exceed 900W unless you hang several more computers on the system. However, you do have a "brute" of a PSU and it obviously affects the operation of your UPS.

I have a similar APC UPS also rated at 1500VA, but it's physically bigger than your unit and probably a different design. The link below is for the 120V version, but mine is the 230V version. I think the main difference is mine holds two 12V batteries, not one.

https://www.amazon.com/APC-SmartConnect-Interactive-Uninterruptible-SMC1500C/dp/B077Y62GSJ

I had three PCs and monitors running on it yesterday, plus two hardware firewalls and a bunch of network switches. None of them were consuming huge amounts of power, but I don't see any flickering lights when switching on systems.

It may just be that your 1300W PSU would be happier on a 2200VA or 3000VA UPS as regards switch on surge. I'm not suggesting you should go out and buy a 2200W UPS though.
https://www.amazon.com/APC-Smart-UPS-SmartConnect-Uninterruptible-SMT2200C/dp/B077YDWR3Y

Just be aware that high switch on currents can eventually burn out electrical contacts in mains switches and mains relays. I've replaced various switched mains outlet sockets and relays over the years (in series with ATX PSUs) and discovered melted and blackened contacts inside. It can take years before things fail but cheap switches/relays go sooner than quality products.

 

[GreenPan]

Does it happen if there's nothing plugged into it? What if you were to have the computer plugged into the wall and nothing plugged into the UPS...

Did you change any of the settings in the UPS?

I've been trying to do some testing without much luck. It just seems to happen randomly. I haven't been able to get it to click plugging the PC into the wall but it could still be possible

 

[GreenPan]

"It makes the UPS switch from outlet power to battery power just for a moment. I'll also note that the lights sort of flicker"

Not surprising the room lights sometimes flicker. Some ATX PSUs momentarily pull a very high current out of the wall socket (and through your UPS) at switch on.

Some PSUs are worse than others. I couldn't find current surge figures for your 1300W unit, but here is a cheap 550W PSU that pulls a hefty 86.31A from a 230V AC input (my mains is 240V). The switch on surge is usually lower for 115V AC supplies, but can still be quite large. With any luck, your Asrock PSU will have a better designed inrush current limiter.

https://www.tomshardware.com/reviews/xpg-pylon-550w-power-supply-review/2

Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. A large enough inrush current can cause circuit breakers and fuses to trip. It can also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current a PSU has right as you turn it on, the better.

It's good to see your APC UPS is rated at 1500VA/900W. I doubt you'll ever exceed 900W unless you hang several more computers on the system. However, you do have a "brute" of a PSU and it obviously affects the operation of your UPS.

I have a similar APC UPS also rated at 1500VA, but it's physically bigger than your unit and probably a different design. The link below is for the 120V version, but mine is the 230V version. I think the main difference is mine holds two 12V batteries, not one.

https://www.amazon.com/APC-SmartConnect-Interactive-Uninterruptible-SMC1500C/dp/B077Y62GSJ

I had three PCs and monitors running on it yesterday, plus two hardware firewalls and a bunch of network switches. None of them were consuming huge amounts of power, but I don't see any flickering lights when switching on systems.

It may just be that your 1300W PSU would be happier on a 2200VA or 3000VA UPS as regards switch on surge. I'm not suggesting you should go out and buy a 2200W UPS though.
https://www.amazon.com/APC-Smart-UPS-SmartConnect-Uninterruptible-SMT2200C/dp/B077YDWR3Y

Just be aware that high switch on currents can eventually burn out electrical contacts in mains switches and mains relays. I've replaced various switched mains outlet sockets and relays over the years (in series with ATX PSUs) and discovered melted and blackened contacts inside. It can take years before things fail but cheap switches/relays go sooner than quality products.

This is the closest I can get for the inrush current
https://hwbusters.com/wp-content/uploads/2024/12/inrush_current_115V-1.png

It's the Taichi which is the higher tier version of the PSU I have but it was $400 vs. $230 and seemed to be almost the exact same so I didn't buy it. Not sure if the inrush current would be similar.

The weird thing is the pop doesn't always happen, only sometimes and I haven't been able to figure out what triggers it. It's paired with a 5090 and 9800X3D but that shouldn't matter

 

[GreenPan]

It seems to indeed be large inrush current overloading the circuit momentarily. I notice that if I don't turn anything else on before turning on the PC, nothing happens. It's only when multiple other things are running

"It makes the UPS switch from outlet power to battery power just for a moment. I'll also note that the lights sort of flicker"

Not surprising the room lights sometimes flicker. Some ATX PSUs momentarily pull a very high current out of the wall socket (and through your UPS) at switch on.

Some PSUs are worse than others. I couldn't find current surge figures for your 1300W unit, but here is a cheap 550W PSU that pulls a hefty 86.31A from a 230V AC input (my mains is 240V). The switch on surge is usually lower for 115V AC supplies, but can still be quite large. With any luck, your Asrock PSU will have a better designed inrush current limiter.

https://www.tomshardware.com/reviews/xpg-pylon-550w-power-supply-review/2

Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. A large enough inrush current can cause circuit breakers and fuses to trip. It can also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current a PSU has right as you turn it on, the better.

It's good to see your APC UPS is rated at 1500VA/900W. I doubt you'll ever exceed 900W unless you hang several more computers on the system. However, you do have a "brute" of a PSU and it obviously affects the operation of your UPS.

I have a similar APC UPS also rated at 1500VA, but it's physically bigger than your unit and probably a different design. The link below is for the 120V version, but mine is the 230V version. I think the main difference is mine holds two 12V batteries, not one.

https://www.amazon.com/APC-SmartConnect-Interactive-Uninterruptible-SMC1500C/dp/B077Y62GSJ

I had three PCs and monitors running on it yesterday, plus two hardware firewalls and a bunch of network switches. None of them were consuming huge amounts of power, but I don't see any flickering lights when switching on systems.

It may just be that your 1300W PSU would be happier on a 2200VA or 3000VA UPS as regards switch on surge. I'm not suggesting you should go out and buy a 2200W UPS though.
https://www.amazon.com/APC-Smart-UPS-SmartConnect-Uninterruptible-SMT2200C/dp/B077YDWR3Y

Just be aware that high switch on currents can eventually burn out electrical contacts in mains switches and mains relays. I've replaced various switched mains outlet sockets and relays over the years (in series with ATX PSUs) and discovered melted and blackened contacts inside. It can take years before things fail but cheap switches/relays go sooner than quality products.

 

[Misgar]

I notice that if I don't turn anything else on before turning on the PC, nothing happens.

It's worth mentioning the ATX PSU inrush current occurs the instant mains is applied to the circuitry inside the ATX PSU. This typically happens when you flip the switch on the rear panel of the PSU to the ON position (assuming the power cord from the PSU is already connected to the AC mains or UPS output).

You will not see a massive current surge when you press the power button on the front of the computer. The PSU is already running, so the current will increase from a few tens or hundreds of millAmps to several Amps, as the load increases. When you start up a game or render task, the current will increase again.

I'm ignoring very fast transient spikes (in the order of milliseconds) drawn by a large GPU or CPU. It's just the initial AC mains switch on surge into the PSU that's concerning us here. This is mostly down to the 420V bulk electrolytic in the PSU looking like a short circuit when power is first applied, but an MOV limiter reduces the amplitude of the current spike in many PSUs.
https://www.tomshardware.com/reviews/power-supplies-101,4193-9.html

I notice that if I don't turn anything else on before turning on the PC, nothing happens. It's only when multiple other things are running

Presumably when "many other things are running" they're all drawing current from the UPS. That reduces the "headroom" available for the ATX PSU switch on current spike, making it more obvious.

An option might be to fit a professional mains filter between the UPS output and the ATX PSU. If your local mains is a nominal 115V AC and your ATX PSU is 90% efficient at 1300W, total power draw could reach approx 1450W, so that's nearly 13A (continuous). You'll never see this in real life.

The minimum rating I'd pick would be a 16A mains filter, e.g. the FN2020-16-08 from Schaffner:
https://uk.farnell.com/schaffner/fn2030-16-06/filter-1-ph-16a-chassis-mount/dp/1304848

I've underlined the section which might apply to your UPS/PSU problem.

FN2020-16-08 Schaffner EMI Filters for industrial applications like motor drives and machine tools. Furthermore, these types of filters are also suitable for mainframe computer systems, large uninterruptible power supplies, medical equipment, wind turbine power stations and a vast array of other three-phase power electronics. Line reactors, also operated on the line side of power drive systems, efficiently protect inverter electronics and DC link capacitors from inrush, peak and short-circuit currents. Additionally, low-frequency interference and harmonics are reduced significantly.

You can also buy this range of filters in 20A and 30A continuous current rating.

Of course you'll need to get a qualified electrician to protect the live terminals by mounting the filter inside an earthed metal box or plastic box, but it's worth a try.

N.B. APC do not recommend fitting third-party surge arrestor strips between some of their products and the wall outlet. It can interfere with UPS operation.