Small PC Build and SF750 are passive even when the power draw is higher than 550W

[PawelC]

Hey, I have a situation in which my SF750 is not starting the fan. I am aware that fan-less mode exists here and he should be silent. 
My specs:
Custom Loop and->
Fatal1ty B450 Gaming-ITX/ac
RTX 3080 T Gigabyte Aourus (water cooled)I ->OCed to the max he can give. He is drawing like all  time 450W
Ryzen 3600 1.4v  4.5 GHz all core  (water cooled)  -> 100w when full load
2x8 DRR4 Corsair 3000 mhz
SSD 256gb
etc.

So, the overall load should be around 550w+ (probably around an average of 600w). 

The power supply is so hot that I can't even touch it because it is so hot. 
I checked. The fan isn't blocked by anything.  He can spin freely. 
I have also one on my main PC AX1600i and he starts spinning slowly when I go over 600w ( normally there is like 800w-900w load).
That is why I think this isn't normal for sf750 not to spin when I am drawing almost 600w on a 750w unit. 

Does anyone have such a problem? Or r this is normal for this PSU?

[LeDoyen]

i am more surprised that your AX1600i spins at 600W to be honest.

For the PSU, hot to the touch doesn't mean too hot for the components inside. most people start to have a burning sensation when touching surfaces around 55- 60°C which is still low enough fo a PSU not to start the fan.

If i take my HX1200i as a reference, after gaming for a while it often stabilizes around 61 - 63°C on a hot day without the fan running.

 

[PawelC]

I checked and in red place i have temp probed. In that place is 87 °C. I can't even touch that place. When the Fan is still not spinning. 

And a screenshot of the power load.
 

Edited December 14, 2023 by PawelC

[PawelC]

I opened SF750 and installed cable from Arduino cables pins to the mobo and setup custom curve as I have a refurbished version and temps aren't best for components. A special like around 90 degrees. We can close the thread!! 

[LeDoyen]

80° on the actual enclosure is crazy !

ther's a problem indeed ^^' so you drive the PSU fan based on a temp sensor you put in there?

[PawelC]

I based on CPU temps. If it is over 60 degrees I go for 30% on PSU and this is fine. I use Arduino cables to connect the fan directly to the motherboard. Because I don't have a warranty as this was a refurbished unit.