Just because you start a new thread doesn't mean you're going to get different answers. I firmy stand behind my previous post
you can change the fan... but you would be better off scrapping that Ultra psu and getting a real psu. *(ultra makes some of the worst psus ever! they have been known to blow up!)
I would never put an ultra anywhere near one of my systems, and I would never put money into one to change the fan out... even if I got it for free... hell you'd have to pay me money to get me to use one.
btw... fill in your rig specs in the user cp
I also think that Fishie had a good point
The fan spins up for a reason so if you replace it with a slower fan it's just gonna overheat... don't do it.
If you want a quality quiet PSU look in to the seasonic series. They are insanely efficient so there's a lot less heat being output... hence no need for noisy fans.
thread is here: http://www.overclock.net/power-suppl...worth-fan.html
I still don't think you should bother to change out the fan for the reasons previously mentioned. Plus, if you do change the fan you void the warranty (not that I've never voided any of my warranties...) Furthermore, before you can do so you need to see if your psu uses a standard fan (120x25mm) I have seen some psus that use skinnier fans.
If you want a queit fan look to Yate Loon. they make some of the best silent fans money can buy and are relativly cheap Seasonic uses Yate Loons in their S12 series of PSUs