Corsair RM850 fan not turning

[s1lence1]

This is probably a no-brainer, but I turned on my computer this morning and the internal power supply fan never moves. It's a Corsair RM850 and I just wanted to make sure this isn't normal. It's would be my luck that it would have an internal switch that only uses the fan when needed.

Thanks!

 

[Barty1884]

There's thermal sensors in the RM850... meaning the fan won't spin up until a certain internal temperature is reached.
Don't recall what it is off-hand... Probably 40'C or so.

Looks like 40'C under full load.
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story3&reid=369

A review of the RM750 states 50% load at 45'C fanless.
https://www.hardocp.com/article/2013/11/13/corsair_rm750_750w_power_supply_review/9#.UtVQNfQW1x0

So, provided you're not experiencing any issues/random shutdowns etc - it's totally fine.

 

[s1lence1]

The computer freezes up, the power supply gets VERY hot but the fan still never turns on. I dont have a temp gauge but i'm assuming it's well above 45c because it is too hot to touch.

 

[Barty1884]

What kind of load are you putting on it?

What are your system specs? And what are you doing when it freezes?
It's possible the sensor (or fan) is defective & it should, in fact, be ramping up.

But under relatively moderate loads, in a fairly modern single-GPU setup, I'd be surprised if it was getting up to (or beyond) 45'C overly fast.

 

[s1lence1]

It's in a machine I use for playing graphic intensive games, 4.0 processor 32gb ram gtx780 gpu so it sees a decent amount of load. I also have 5 case fans I put in the NZXT case I built it in but I don't think theyre enough to compensate for a bad internal. I'm going to borrow my stepson's thermal gun and if it's above 45c i'll know for sure but im almost positive it is.

 

[Rexper]

A lot of Corsairs use an MCU to also factor the relative load in its fan curve. I can’t say if your specific unit does.

As seen from this review https://www.techpowerup.com/reviews/Corsair/RM850/5.html
The fan was found spinning at 80% load. While the ‘Temp in’ for the previous test was just shy of 55°C.

 

[Barty1884]

Unless your CPU was one of the higher TDP FX chips (like the really high 200+W chips) and the 780, you're likely around 400W absolute peak.
Which would be <50% load on the RM850.