Corsair Rm1000i PSU Pop Noise When Turning on Sometimes

ltron · 19 May 2019 at 14:27

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

ltron · 19 May 2019 at 16:39

Radox-0 said:
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.

ltron · 19 May 2019 at 20:23

EsaT said:
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.

ltron · 22 Jun 2020 at 18:33

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.