Does power supply orientation really matter?

So basically I bought a Corsair Ax860i about a month ago and its been working flawlessly, no clicking sounds from the fans, no unusual fan ramping up and down even though in link I do see that the fan seems to go to 500 rpm every few seconds, not sure if that is gonna wear it out or not. But no clicking so far. as to my question. Does the orientation of my PSU really matter. At the moment I have it with the fan facing down. I have read that this makes the heat travel up into the PCB and goes again natural cooling when the fan is off. I monitored the temps on the unit when I was gaming for a few hours and at most it got about 38.5-39c over a few hour period. I have one of those MSI r290 gaming 4g video cards that is non reference and it seems to put quite a bit of heat into the case. see attached pic







So with this setup and alot of air being dumped into the case, would it be best to leave as is (fan facing down) or put it right side up with potentially very warm air being pulled into it and counterbalancing the natural process of heat rising off the pcb? I could see in a computer with a reference graphics card flipping it helping, but I'm confused on this and honestly don't want to move wires around if I don't need to just to experiment.

Does power supply orientation really matter?