Corsair Rm1000i PSU Pop Noise When Turning on Sometimes

[ltron]

About 1-2 times per month when turning on my Rm1000i using the switch on the back of the PSU it will make a pop noise, the volume varies: sometimes this is quiet and other times it's very loud.

I found this thread where jonnyGuru mentions an NTC thermistor and a bypass relay which is supposed to protect against high inrush current when you turn the PSU on: https://linustechtips.com/main/topic/890449-rm650x-makes-a-popping-noise/?page=2

I also found a few threads on OCUK so this seems to be fairly common. I did some detective work and I found something rather interesting: the RM1000i and old gen RMx power supplies don't even have a bypass relay, they only have an NTC thermistor!

I am not an expert so could be talking rubbish, but could this be the cause of our problems as inrush current in the UK is significantly higher due to the 230V AC voltage and people with this problem seem to reside in the UK?

Rm1000i only has an NTC thermistor, no bypass relay: https://www.techpowerup.com/reviews/Corsair/RM1000i/4.html

Old gen RM750x no bypass relay: https://www.tomshardware.com/reviews/corsair-rm750x-power-supply,4303-3.html

New gen RM750X does have bypass relay: https://www.tomshardware.co.uk/corsair-rm750x-v2-psu,review-34387-3.html

RM650X v1 and 850X v2 why having a bypass relay is desirable: https://www.tomshardware.co.uk/corsair-rm650x-psu,review-33614-3.html https://www.kitguru.net/components/...itziopoulos/corsair-rm850x-2018-psu-review/3/


Given some people's Corsair PSUs have exploded or at least the NTC thermistor has, should I be worried? By the way, the PSU has been working fine for the 3.5 years I've used it but the popping noise is unnerving and I've noticed it started over the last 2 years or so, although it happens infrequently.

This person on the Corsair forums has had the problem with multiple RM1000i PSUs so I'm not sure whether RMAing will help: http://forum.corsair.com/v3/showthread.php?t=167956

 

[Radox-0]

I had this with my HX1200i, though apparently that does have a bypass relay. Mine manifested about 2 years and like yours happened after I turned the PSU on from the wall from the first time from cold boot. Was ******* scary to be honest at times and eventually noticed sparks appearing along with the noise. I actually had the exact same issue as the guy in that corsair thread. When I took it out the system small black bits fell through the vent. Mine is similarly not plugged into a power strip, directly to wall socket.

I RMA'd mine and received back a brand new wrapped replacement. Not unsealed it though as I have a AX1600i (needed it as HX1200i was too small to OC system with anyways) and not had an issue so far with the AXi unit.

 

[ltron]

I had this with my HX1200i, though apparently that does have a bypass relay. Mine manifested about 2 years and like yours happened after I turned the PSU on from the wall from the first time from cold boot. Was ******* scary to be honest at times and eventually noticed sparks appearing along with the noise. I actually had the exact same issue as the guy in that corsair thread. When I took it out the system small black bits fell through the vent. Mine is similarly not plugged into a power strip, directly to wall socket.

I RMA'd mine and received back a brand new wrapped replacement. Not unsealed it though as I have a AX1600i (needed it as HX1200i was too small to OC system with anyways) and not had an issue so far with the AXi unit.

I see, I wonder what's wrong with these Corsair units as it seems to be quite common. I realised after I posted that people have been having problems with Corsair PSUs with the relay too so it can't be that although it should help. JonnyGuru's (former famous PSU reviewer although has held a high position in Corsair's PSU division for many years now) suggestion to never turn your PC off at the mains is just laughable, I want to be able to do so and I don't like leaving electronics on overnight and a PSU should be able to accommodate such basic functionality.

I was thinking I'll replace the PSU in light of this problem when I upgrade to Zen 2 later this year. I don't need 1000W anymore and this Seasonic PSU has got stellar reviews: https://www.overclockers.co.uk/seas...-titanium-modular-power-supply-ca-061-ss.html

I just hope it doesn't have the same problem.

 

[Radox-0]

Yeah saw that suggestion too when I was trying to understand what was going on a while back. Like you generally turn the power off from the wall socket when not planning to use for a while / overnight so not too impressed with that suggestion.

 

[EsaT]

the RM1000i and old gen RMx power supplies don't even have a bypass relay, they only have an NTC thermistor!

Relay is there to bypass NTC after PSU is powerred on to avoid power loss in NTC.
Relay should be normally open type and leaving NTC into current path if relay malfunctions.

Though I guess it's possible that without relay there that continuous heating might eventually damage NTC causing some kind permanent low resistance/shorted state.
Not sure what kind failure modes NTCs have, but for some components shorting is one of the failure modes.
Again if NTC burns open PSU shouldn't get any power.

 

[ltron]

Relay is there to bypass NTC after PSU is powerred on to avoid power loss in NTC.
Relay should be normally open type and leaving NTC into current path if relay malfunctions.

Though I guess it's possible that without relay there that continuous heating might eventually damage NTC causing some kind permanent low resistance/shorted state.
Not sure what kind failure modes NTCs have, but for some components shorting is one of the failure modes.
Again if NTC burns open PSU shouldn't get any power.

Thanks for the explanation, it seems I misunderstood the purpose of the relay. Do you have any insight into the popping noise when I turn the PSU on and is it harmful to the PSU given it happens very infrequently (1-2 times a month) in my case? Is there anything I can do to stop it from happening?

The PSU is still working really well and voltages are excellent and very stable.

 

[EsaT]

If noise comes because of NTC having failed and not limiting capacitor charging surge, there isn't anything which could be done.
Of course if connection happens at precise moment of mains voltage being nearer zero, then it's possible for current to start more gradually.

But if connection happens at peak voltage near 340V that'll kickstart things...
With empty capacitor being pretty much short circuit.
Like discharge in reverse:
https://www.youtube.com/watch?v=hbxJDoi3cpk

That could be reason why you don't always hear loud noise.

Higher surge is definitely putting lot more wear on any switches or contacts of power cable plug.
Likely it could also have some effect to primary side components in path of that current.
Secondary side outputting voltages is galvanically isolated and won't be affected.

 

[Armadillo]

Had popping on mine sometimes (HX750i). NTC thermistor had cracks all over it. Replaced it (was out of warranty) and no pops since.

 

[Radox-0]

Had popping on mine sometimes (HX750i). NTC thermistor had cracks all over it. Replaced it (was out of warranty) and no pops since.

Yeah sounds like what I had and likely similar failure point.

Though how was the unit out of warranty? HXi models only released middle of 2014 at the earliest and have a 10 year warranty.

 

[Armadillo]

Yeah sounds like what I had and likely similar failure point.

Though how was the unit out of warranty? HXi models only released middle of 2014 at the earliest and have a 10 year warranty.

It was already a warranty replacement. Nothing but bad luck with Corsair supplies here, so was already a replacement for a hx750, which was a replacement for a tx650 and warranty runs from the original supply/purchase, so out of warranty.

 

[Radox-0]

It was already a warranty replacement. Nothing but bad luck with Corsair supplies here, so was already a replacement for a hx750, which was a replacement for a tx650 and warranty runs from the original supply/purchase, so out of warranty.

Ahhh, that sucks massively.

 

[rio2]

Had popping on mine sometimes (HX750i). NTC thermistor had cracks all over it. Replaced it (was out of warranty) and no pops since.

What value did you use, I need to replace the cracked NTC in my HX750i, but the print is burned?

 

[Armadillo]

What value did you use, I need to replace the cracked NTC in my HX750i, but the print is burned?

I don't know what the original value was either, mine was missing as well. In the end I replaced it with an mf72 5d20.

I searched and asked and consensus seemed to be it's just limiting inrush, so it doesn't matter too much, just use something similar value. I searched and looked at reviews of lots of 750w supplies and of those I could see the markings, it was mostly 5dxx. So 5ohms. So I went with a 5d20, slightly bigger diameter than the one that was in there and what seemed to be in most others, but can take a higher max current, so hopefully won't crack.

Legs on a 20mm one where a little harder to get through the holes (fat legs), but did go through. Probably could have gone with a 5d15, but wanted to go with the highest max current I could fit because of the other one literally killing itself.

Not sure if the advice was good or not, but it's been running fine with the 5d20 for nearly two years with no issues at all.

 

[ltron]

Sorry to necro, but a component in my Corsair RM1000i blew up on turning the PSU on one day and the PSU is in the process of being RMAd; it's confirmed dead with a PSU tester (other than being able to provide 5V standby voltage). It seems like I was right to be worried about the PSU making a popping noise as when I took it out of the PC little bits of metal wire and a green object fell out of the fan grill, from looking through the fan grill a small section of the PCB also seems to be cracked probably due to the component exploding.

Pics:




Corsair's jonnyguru says it's a 'part of a metal-oxide varistor used for surge suppression inside the PSU' and that I should just leave the PC plugged into the mains at all times and never turn it off at the wall or turn it off using the switch on the back of the PSU. I'll to do it, but I wonder whether a design flaw is making these PSUs vulnerable to being turned off and on constantly.

I'm having great service with my Corsair RMA though so this is not intended to bash them.