I have a spare 80mm fan, and I was wondering how to use it, and I thought about putting in on my PSU. It would be on the outside because there is no place inside and it's also easier. What I wanna know is if it's a good idea. I also don't know if I should make it as an intake or exhaust fan since the psu has already a 120mm intake fan, but it is still running alittle warm...need opinion for that too.

Thanks.

P.S. - I don't know with what to mount it....I wanna try and do it without taking the PSU apart, and also if possible without removing it from the case since all my cable management will be ruined. I can although unscrew it and mov it around so it's more comfortable to work with.

Personally I probably wouldn't bother.
I'd say you would be better off making sure your case airflow is optimal if you want your PSU to run a bit cooler (i.e. make sure the air it's sucking in isn't too warm already).

I would expect the PSU exhaust temperature to be reasonably warm as well, though if you have a way of measuring it, you could do that.

As long as the screws that you use do not puncture anything or short anything I think that you'll be fine.

I would mount the fan as an exhaust to help pull air out of the PSU.

It should have mesh or some sort of metal slots on the back of the PSU, those holes are perfect for screw threads.

As far as powering the fan goes just pass the molex connector through an available hole (a PCI slot works good) or run it between the case and the sidepanel.

Yup, the back side is grilled, so I guess screws would fit, but how do I put them... I don't want to take apart the psu, and seems that this is the only way to use screws. I could use some of those plastic thingis that are used on some psu's in order to keep some cables together, I don't know where to buy em from though...

Correct me if I'm wrong, but I think what Andrew means is get some screws where the threads are just a bit bigger than the mesh and make your own threads with the screws, like what you do with a fan casing.

You can get zip-ties at any store like walmart.

Ah zip-ties is what they were called. XD One little problem - fan doesn't fit...It's a little too big. ...I guess I could take the fan from my old CPU stock cooler.