Power Supply Fan Direction

[amigadave]

+1.  If I'm trying to make a machine last, I add more small fans to blow on the the hot stuff and stir the air.  Then I feel better about using the PS fan to inflate the case.  

The real benefit of reversing the PS fan is controlling dust that is normally drawn in thru the floppy drives, etc.  After the PS fan is turned to blow in, an air filter should be added to the back intake.  It is then a simple matter to clean the air filter periodically (much easier and safer than cleaning out a floppy drive).

Compared to modern CPUs and graphic chips, near stock Amigas don't generate near as much heat.

I think you misunderstood what the OP wrote, as he has reversed the fan to "exhaust" the heat, or blow outward into the room, not into the case.

I would not want the heat generated by the PSU to be blown into any of my computers, so would not do as you suggested by reversing the fan to blow through the PSU "into" the case and placing a filter material over the air intake at the back of the PSU.  I would always add at least one additional fan to blow air into the case and across any heat generating components, with an appropriate filter to keep out unwanted dust as much as possible. This would also compensate for the air being exhausted by the PSU fan, so little or no air would be drawn in through the floppy drive openings, and reduce the amount of dust drawn into the case from anywhere by the PSU fan sucking air out of the case.

[QuikSanz]

Nope. Most of them are electronically commuted, i.e. by a small chip in the fan. The electronics requires the power supply exactly in the specified direction. The only way how to reverse a DC brushless fan is just to install it the other way around.

Brushless motors are 3 wire,usually 1 more for speed sensing. I specify 2 wire only because of this.

Chris

[QuikSanz]

All fans are marked (with arrows) to tell which way they rotate and which way the airflow is.

Yup, The fan itself is an airfoil designed for blowing in 1 direction only and very efficient at it.

Chris

[Brian]

The tech is an idiot. Yes the lifespan of you PSU might increase as it gets cooler air from outside however the system now not only have to cope with the heat it produces self but also the heat from the PSU and the hole computers lifespan will decrease.

Reverse it so it pull air back out again and if you are worried about system temp add fan(s) to pull in air from the front. There's plenty of room behind the front bezel to hide slim fan(s) and they can be placed near the cutout next to the zorro slots or you can drill a hole in the metal where you see fit (or both)... you can even drill holes in the backplates where there's no cards installed for better airflow over the cards that are installed.

[AmmoJammo]

Brushless motors are 3 wire,usually 1 more for speed sensing. I specify 2 wire only because of this.

Chris

There is not a single 2 wire or otherwise, computer fan, that can be wired backwards to run backwards.

[gertsy]

While I agree fresh air intake is optimal, when you only have one fan in the system your first priority should be to exhaust the heat...otherwise it has nowhere to go and gets trapped...I went ahead and switched it around myself...first time opening a PSU and nobody got hurt:roflmao:

+1 Good move. I love the fact that you ably fixed it was ignored by the thread. LOL.

[Dandy]

PSU is most likely going to be the hottest part in the computer, so I'd be having it blowing air out the back of the case.

Either way will probably be ok, but as its also the highest vent in the case, having it blowing IN, isn't going to work so well when convection comes into play.

In my towered A4000PPC I have 4 fans:
1 in the PSU (blowing the hot air out)
1 on the PPC CPU
1 on the Voodoo4 GPU
1 mounted at the back of the tower casing - sucking air in through a dust filter and blowing it onto the two cpus on the CSPPC through a selfmade cardbox sort of tube thing.

This has the advantage that there is no depression inside the tower and so no air is sucked in through all the small gaps like between the CD drives/DVD drives/tape streamer/floppy disk drives and through all the small gaps among the slot brackets on the backside. In all these small gaps dust sedimented and even in the gaps of the (closed) CD/DVD drive tray drawers (and inside the drives as well, of course) or USB slots.

Since I have it this way I could cancel the regular, painstaking cleaning of all the gaps and the innards of the drives - I just have to renew the dust filter on the casing fan from time to time...