SF600 Fan controller

Hi, so Ive got this new PSU in my ITX build, the case ive got has very restricted airflow, in fact it has no exhaust fans at all :eek: Its the Silverstone Milo ML-08.

My temps are surprisingly good and generally when browsing the fan on the PSU stays off in its hybrid mode. When under load it spins up, makes a little noise, all fine. Then it never seems to spin down when not under load again, Ive left it for an hour or so idling on the desktop. I have to shut down my machine for a few minutes then when rebooting it stays off like normal.

Does anyone else have this issue?

What I think could be occurring is that while load is going down the temps are not going below a certain threshold? Maybe hot air is trapped inside the PSU because of my airflow? The unit gets good intake, the fan is right next to an external vent so it gets fresh air fine just not sure where the exhausted hot air goes.

Could I reverse the fan on my PSU so it acts as an exhaust drawing air through the PSU case to cool it down and out through the vents? Will this void the warranty? Will this even work?

Also going to try reversing my CPU fan first to act as an exhaust but this will create perhaps too much negative pressure and I think this case works well because of positive pressure helping the hot air escape (and keeping the dust out).

Just for reference sake:

i7 6700k not overclocked

Thermalright AXP-100 Muscle

GTX 1070

Temps:

Idle 28-30 C

Load 76-78 C

Edit:

Okay did a few tests. Had my case lay flat so hot air could more easily escape upwards. Fan stayed off during CPU test but came on after CPU fan slowed after benchmark. It looks like in a vertical position the PSU exhausts air downwards into a chamber where it can escape through a vent, not sure how efficient that is. Fan stayed on indefinitely afterwards. Tried case upside down so exhaust air comes out of the top, fan stays on even when there is no load. I can get the fan to stop by using another fan to blow cool air inside the psu which leads me to believe that it cannot exhaust enough warm air to get under the threshold to stop again. Even when I get the fan to stop by blowing cool air in it starts again after 2 minutes of idling.

Ambient temp of room about 18 C

Same issue. Is there a way to force the fan on? Or control it at all?

Only on 'i' series power supplies.

The fan itself is controlled by an internal temperature sensor and controller. With the 'i' series coolers, you have the ability to control it yourself but it's always there and will turn on when needed.

Basically, that's how a fan works.

The start up voltage of a fan is much higher than the voltage required to maintain it spinning, that's why it won't stop again. I bet if you poked it it will stop.