lafoxxx wrote:

The system itself works flawlessly, no overheating issues so far.

That's kind of the key factor.

I have seen a PSU like that before, but I don't know which way it pushed air. I think there were a handful of commercial "overpressure" systems with more air blowing into the system than out, as a way to try to prevent dust buildup. Don't know if this is one of those.

If you want to change it, check temps under loads (especially if you have a non-contact thermometer), then flip it and check again under load.

And good luck!

lafoxxx wrote:

Because now it looks like (I checked) it's blowing air from the back of the computer, through the PSU, to PC case (CPU fan area).

Why would they do that?

For systems using a CPU with passive cooling, or for BTX form factor. This is completely legit. Of course, when building a system with such an PSU, you have to make sure that all other fans are following the air flow - e.g. you can not have all fans blowing air into the case.

Did some research on ATX PSU and decided to flip it over, basically making the air go outside through the PSU.

Looks better -- no 'loop'. Didn't manage to check the temps yet, but I guess it'll be fine for now

Too bad the fan is too big to be placed inside the PSU. There's still some area inside allowing me to place a (smaller) fan in the back (near the power supply socket) as an exhaust, like in most PSUs.

I've seen plenty of older style ATX power supplies do this, mostly OEM iirc.

Things like Pentium IIs and IIIs which didn't have fans used the power supply fan to cool the CPU. Usually there was a shroud as well. One of my HP Vectras does something similar for it's Pentium 1, but it is not even close to ATX.

Probably meant to have a plastic shroud for cooling the CPU

lafoxxx wrote:

Have you guys ever seen (old) PSU with fan mounted outside?.

Yes have seen outside mounted fans. That looks like a Sparkle power psu, I had a PowMax that was similar but it did indeed blow outward not inward.

FAMICOMASTER wrote:

I've seen plenty of older style ATX power supplies do this, mostly OEM iirc.

Yes like some odd Dell or Compaq but that appears to be an after market type from the appearance

I think I'll be replacing the fan at some point. Too noisy.
Would most PVM fans work? There's 2 pin DC connector, but I've seen a video of some guy swappng their (modern) PSU fan with Noctua, and it didn't work when PSU DC connector was used.

This was pretty common, especially in OEM SFF machines a la Vectra series, for example.

Early PIII Slot1s came in passively and actively cooled variants. Regardless of the Slot1 CPU having an additional fan or not, the air would have been sucked in via the PSU on the back and blown into the chassis into the direction of the Slot1 CPU (these PSUs were usually only 70-100watt PSUs so the air coming out of them was usually always still rather chilly). A slight airstream blown into the general direction of the Slot1 CPUs was in most cases way enough to keep them adequately cooled.

Sidenote: I actually reversed this airflow in my Vectra. As it is now fully packed (fully populated expansion area, amongst others with V2 SLI, which can get rather warm), I have added a low noise Noctua fan at the front of the machine, which sucks in air and blows it into the direction of the expansion compartment. The fan in the PSU is reversed, so it now sucks the air out of the back, resulting in a moderate airflow from front to back.

Also the fans inside these PSUs are more often than not of the slightly narrower variety, so keep that in mind and check their dimensions before ordering spare fans.